Chapter LXXXII: Part 2 (43)

-------+-----------------------------------------------------------
Fluid | Specific
Ounces.| Gravity.
+----+----+----+----+----+----+----+----+----+----+----+----+----
|1003|1004|1005|1006|1007|1008|1009|1010|1011|1012|1013|1014|1015
-------+----+----+----+----+----+----+----+----+----+----+----+----
20| 35| 36| 43 | 57 | 71 | 85 | 100| 103|106 | 119| 130| 136| 142
22| 38| 40| 47 | 62 | 78 | 95 | 110| 113|116 | 130| 149| 142| 156
24| 42| 43| 51 | 68 | 85 |101 | 120| 123|127 | 142| 156| 163| 170
26| 45| 47| 55 | 73 | 92 |110 | 130| 131|137 | 153| 169| 176| 184
28| 48| 50| 59 | 79 | 99 |118 | 140| 144|148 | 165| 182| 190| 198
30| 52| 54| 64 | 85 |106 |127 | 150| 155|159 | 177| 195| 204| 213
32| 55| 57| 68 | 90 |113 |135 | 160| 165|169 | 188| 208| 217| 227
34| 58| 61| 72 | 96 |120 |144 | 170| 175|180 | 200| 221| 231| 241
36| 61| 64| 76 |102 |127 |153 | 180| 185|191 | 212| 234| 244| 255
38| 65| 68| 80 |108 |134 |161 | 190| 195|201 | 224| 247| 258| 269
40| 69| 72| 85 |114 |142 |170 | 200| 206|212 | 236| 260| 272| 284
42| 74| 75| 89 |119 |148 |178 | 210| 216|222 | 247| 273| 285| 298
44| 76| 79| 93 |125 |156 |186 | 220| 226|233 | 259| 286| 299| 312
46| 80| 82| 96 |130 |163 |195 | 230| 236|243 | 271| 299| 312| 326
48| 84| 86|101 |136 |170 |203 | 240| 246|254 | 283| 312| 326| 340
50| 87| 90|106 |142 |178 |212 | 250| 257|265 | 295| 325| 340| 355
52| 90| 94|110 |147 |185 |220 | 260| 267|276 | 307| 338| 353| 369
54| 94| 98|114 |153 |192 |229 | 270| 277|286 | 319| 351| 367| 383
56| 96| 100|119 |159 |199 |238 | 280| 288|297 | 331| 364| 380| 397
58| 100| 104|123 |165 |206 |246 | 290| 298|308 | 343| 377| 394| 411
60| 104| 108|128 |171 |213 |255 | 300| 309|310 | 355| 391| 408| 426
62| 108| 110|132 |176 |220 |263 | 310| 319|329 | 404| 421| 440| 468
64| 110| 114|136 |182 |227 |271 | 320| 329|340 | 378| 417| 435| 454
66| 114| 118|140 |187 |234 |280 | 330| 340|351 | 390| 431| 448| 468
68| 116| 122|144 |193 |240 |288 | 340| 350|361 | 402| 443| 462| 482
70| 120| 126|149 |199 |248 |297 | 350| 361|372 | 414| 456| 476| 497
72| 122| 128|153 |204 |255 |305 | 360| 371|382 | 425| 469| 489| 511
74| 126| 132|157 |210 |262 |314 | 370| 381|393 | 437| 482| 503| 525
76| 130| 136|161 |216 |269 |323 | 380| 391|404 | 449| 595| 516| 539
78| 134| 140|165 |222 |276 |331 | 390| 401|414 | 461| 508| 530| 553
80| 139| 144|170 |228 |284 |340 | 400| 412|445 | 473| 521| 544| 568
——+----+----+----+----+----+----+----+----+----+----+----+----+----

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Fluid | Specific
Ounces.| Gravity.
+----+----+----+----+----+----+----+----+----+----+----+----+----
|1016|1017|1018|1019|1020|1021|1022|1023|1024|1025|1026|1027|1028
-------+----+----+----+----+----+----+----+----+----+----+----+----
20| 151| 160| 196| 233| 241| 249| 257| 265| 274| 276| 278| 279| 280
22| 166| 176| 215| 257| 265| 274| 282| 292| 301| 303| 305| 306| 308
24| 181| 192| 235| 280| 289| 299| 308| 319| 329| 331| 333| 334| 336
26| 196| 208| 254| 303| 313| 324| 334| 346| 356| 359| 360| 362| 364
28| 221| 224| 274| 326| 337| 349| 360| 372| 383| 386| 388| 390| 392
30| 226| 240| 294| 349| 361| 374| 386| 399| 411| 414| 416| 418| 420
32| 241| 256| 313| 373| 385| 398| 411| 425| 438| 442| 443| 446| 448
34| 256| 272| 333| 396| 409| 423| 437| 451| 466| 469| 471| 474| 476
36| 271| 288| 352| 419| 433| 448| 462| 477| 493| 497| 499| 502| 504
38| 286| 304| 372| 442| 457| 473| 488| 503| 520| 524| 527| 530| 532
40| 302| 320| 392| 465| 484| 498| 514| 530| 548| 552| 555| 558| 560
42| 317| 336| 411| 489| 506| 523| 540| 557| 575| 580| 582| 585| 588
44| 332| 352| 431| 512| 530| 548| 556| 584| 603| 607| 610| 613| 616
46| 347| 368| 450| 535| 554| 573| 592| 611| 630| 635| 638| 641| 644
48| 362| 384| 470| 558| 578| 598| 618| 637| 657| 662| 666| 669| 672
50| 377| 400| 490| 581| 602| 623| 644| 665| 685| 690| 694| 697| 700
52| 393| 416| 509| 605| 626| 648| 669| 692| 711| 718| 721| 724| 728
54| 408| 432| 529| 628| 650| 673| 695| 718| 740| 745| 749| 752| 756
56| 423| 448| 548| 651| 674| 698| 720| 745| 767| 772| 776| 780| 784
58| 438| 464| 568| 674| 698| 723| 746| 772| 794| 800| 804| 808| 812
60| 453| 480| 588| 697| 722| 748| 772| 798| 822| 828| 832| 836| 840
62| 496| 607| 719| 746| 772| 797| 824| 849| 856| 859| 864| 864| 868
64| 483| 512| 627| 742| 770| 797| 823| 851| 877| 883| 887| 862| 896
66| 498| 528| 646| 766| 794| 822| 849| 877| 904| 911| 915| 920| 924
68| 513| 544| 666| 790| 818| 847| 875| 904| 931| 939| 943| 948| 954
70| 528| 560| 686| 814| 843| 872| 901| 930| 959| 966| 971| 976| 980
72| 544| 576| 705| 838| 867| 896| 926| 956| 986| 994| 998|1004|1008
74| 558| 592| 725| 861| 891| 921| 951| 982|1014|1021|1026|1032|1036
76| 573| 608| 745| 884| 915| 946| 977|1008|1041|1049|1054|1060|1064
78| 588| 624| 765| 907| 939| 971|1002|1034|1068|1076|1082|1088|1092
80| 604| 640| 785| 930| 964| 996|1028|1060|1096|1104|1110|1116|1120
——+----+----+----+----+----+----+----+----+----+----+----+----+----

In urines containing pus, the clear portion should always be examined for albumen, since where this is found, except in small amount, some form of kidney disease may be suspected.

But it sometimes happens that the pus is present in such small quantity in the urine as to preclude its chemical examination. Under these circumstances, recourse must be had to the microscope. Dr Lionel Beale says, “Pus-globules, which have been long removed from the body, always have a granulated appearance in the microscope, and, when fresh, do not always exhibit a well-defined nucleus; the outline is usually distinct and circular, but it is finely crenated. Upon the addition of acetic acid the globule increases somewhat in size, becomes spherical, with a smooth, faint outline, and from one to four nearly circular bodies are developed in the centre of each. If the pus-corpuscles have lain some days in the urine they will have undergone complete disintegration.”

_Epithelium._ A great many varieties of epithelium, derived from different parts of the kidneys, ureters, bladder, urethra, vagina, &c., are more or less present in urine. A few of these are given in the accompanying engraving. In the various diseases peculiar to the urinary and genito-urinary organs the quantity of epithelium present in the urine is frequently considerable, and as in some cases it presents itself in an imperfect or disintegrated form, its identification, except to the experienced microscopist and physiologist, becomes a matter of great difficulty.

_Casts._ Casts or moulds which have been formed in the tubes of the kidneys, or in the uterus and vagina, are constantly finding their way into the urine of persons affected with acute or chronic renal diseases and uterine affections. They are very varied both in character and appearance, and difficult of recognition, except by the skilled microscopist and pathologist.

_Blood-corpuscles._ These, when present in quiescent urine, occur as a sediment at the bottom of the vessel. Some few globules, however, are diffused throughout the supernatant urine, and impart to it a smoky appearance, if the fluid have a marked acid reaction; whereas if the reaction be alkaline the corpuscles assume a bright red colour.

In the accompanying plate the three upper groups represent blood-corpuscles taken from the human body; the three lower those found in urine. Of these latter some will be seen to have lost their circular outline, and to have become jagged or crenated. In some cases, on the contrary, they swell and become much enlarged. These changes in appearance take place when the blood has remained for some time in the urine, and appear to be due to the forces of endosmose and exosmose.

_Fungi._ The chief vegetable organisms found in urine are the _sugar fungus_ and the _Penicillium glaucum_. The sugar fungus is precisely the same as the yeast plant (the _Torula cerevisiæ_). The _Penicillium_ is very frequently present in albuminous urine, with an acid reaction, as well as in diabetic.

_Uric acid._ See back.

_Urates._——According to Bence Jones the soluble urates met with in healthy urine consist of uric acid, potassium, ammonium, and sodium.

In abnormal urine the urates of ammonium and sodium sometimes occur, the latter, which are the more general, presenting under the microscope the appearance shown below.

Urate of sodium is, however, much more common in the urine of children than of adults, when it presents itself in the form of spherical crystals.

In both cases the urates are associated with uric acid (resulting from their partial decomposition), represented by the small spiked crystals protruding from the spheres in the form of needle-shaped crystals. Urate of sodium occurs as the concretions known as ‘chalk stones’ in gout. But by far the most abundant kind of urates met with in abnormal urine is that known as _amorphous urates_, which constitute the most common variety of urinary deposits.

Heintz states that they are a mixture of urate of sodium with small quantities of the urates of ammonium, lime, and magnesium. They are very frequently seen in the urine of persons in excellent health, in which, owing perhaps to too abundant or nitrogenous diet and an insufficiency of muscular exercise, being in excess, they are thrown down when the urine cools.

An excess of the amorphous urates in urine, like the presence of pus and phosphates, is indicated by the bulky precipitate more or less diffused throughout the vessel containing the urine. A very easy test will decide as to which of the three classes of substances (if only one of them be present) the precipitate belongs. The supernatant fluid being decanted from the deposit, about an equal bulk of liquor potassæ is added to the latter, when one of three results will ensue:

1. If it be _pus_, and become viscid, it will exhibit the qualities already mentioned under the description of that substance.

2. If _phosphates_, no alteration will ensue.

3. If _amorphous urate_, it will at once dissolve.

When amorphous urates are uniformly distributed throughout the urine they give it a milky appearance, which may sometimes lead to its being mistaken for _chylous_ urine, or urine throughout which fatty particles of chyle are diffused. This latter doubt, however, may be easily set at rest by gently heating it. If the turbidity is owing to the urate it will disappear; if to chyle it will remain.

If the amorphous urate be decomposed by a little hydrochloric acid, it will yield uric acid, easily recognised by its characteristic form under the microscope, or when treated with nitric acid and ammonia, will answer to the murexed test.

It sometimes happens that in testing an acid urine suspected to contain albumen, the urine may contain so large an amount of uric acid in solution that, upon adding a drop of nitric acid to it, a bulky precipitate of uric acid, exactly resembling albumen, is thrown down, and it may be erroneously regarded as this substance if examined under the microscope immediately upon its formation. Upon being allowed, however, to stand some time, and then placed under the microscope, the well-known crystals of the acid will reveal themselves.

In such urine no precipitate takes place when the liquid is heated, another essential feature in which it diverges from albumen.

_Phosphates._——The urinary earthy phosphates occur under two varieties, viz. the phosphate of ammonia and magnesia, known as the triple phosphate, and the phosphate of lime.

In the engravings below, the principal crystalline forms of the triple phosphate are shown.

Of these the triangular prismatic, with the truncated extremities, is the most common. In some cases the prisms are so much reduced in length as to resemble the octahedral crystals of oxalate of lime, for which they are sometimes mistaken by the inexperienced. When any doubt exists on this point it must be set at rest by having recourse to the chemical tests given further on. The triple phosphate is rarely met with alone, urate of ammonia, and sometimes uric acid and oxalate of lime, being present, although generally occurring in neutral or alkaline urine. The triple acid is sometimes found in that which is acid.

When ammonia is added to fresh urine the triple phosphate is precipitated, and if it be then examined by the microscope it will be found to consist of beautiful stellate crystals, and to form a most attractive object. The presence of phosphoric acid can be demonstrated by the ordinary reagents.

Phosphate of lime dissolves in strong acids without effervescence. The presence of lime, as well as of phosphoric acid, can easily be verified by the usual tests.

_Oxalate of lime._ The principal crystalline forms of oxalate of lime, when it occurs as a urinary deposit, are the octahedral and the dumb-bell. Of these the most common is the octahedral. These octahedra (which have one axis much shorter than the other two) vary considerably in size, but there is reason to believe that the diversity in appearance which they exhibit is due to crystals of precisely the same shape occupying different positions as to the direction of their axes, when examined by the microscope. There are a great many diversities of the dumb-bell form of oxalate of lime, which seem to be derived from circular and oval crystals. The subjoined cuts illustrate the varieties of crystalline oxalates the most generally met with. When the crystals of oxalate are extremely minute, they are very liable to be overlooked, since they then appear as almost opaque cubes, and may not unnaturally be taken for urate of soda, to which they bear no slight resemblance; but from which they differ by being insoluble in potash or acetic acid, and not dissolving on the application of heat. We have already alluded to their resemblance to the dumb-bells of the earthy phosphates. Another distinctive feature is that the oxalates rarely sink to the bottom of the vessel, but are diffused through the mucous cloud, which forms in urine after a short time.

_Cystine._ Cystine is an occasional ingredient in urine, when it occurs as a whitish precipitate crystallised in hexagonal plates. At other times, but not so frequently, it is met with dissolved in the urine. It may be separated from the urine holding it in solution by the addition of an excess of acetic acid. Under the microscope cystine bears somewhat of a resemblance to uric acid, from which, however, it differs when under treatment with ammonia. When ammonia is added to cystine the cystine dissolves, but by the spontaneous evaporation of the ammonia remains behind in its original form; whilst, if the ammonia be allowed to escape under the same circumstance from the urate of ammonia which has been formed, this remains behind as an amorphous mass. Ammonia, therefore, dissolves the cystine without entering into chemical union with it. Potash also readily dissolves cystine, as do also oxalic acid and the strong mineral acids. It is, however, insoluble in boiling water, in weak hydrochloric acid, and, as we have seen, in acetic acid.

_Obs._ In the examination of urine it is important that the investigation should be conducted upon a portion taken from _the whole of the urine excreted during twenty-four hours_, and not on an isolated quantity voided at any particular time.

The compiler of the present article has to acknowledge his indebtedness to Dr Lionel Beale’s very valuable and exhaustive work, ‘Kidney Diseases, Urinary Deposits, &c.,’ as well as to Dr W. Roberts’s excellent book, ‘Urinary and Renal Diseases,’ to both of which volumes the reader, desirous of further and more explicit information on the subject, is referred.

=URINOM′ETER.= An hydrometer adapted to determining the density of urine. That of Dr Prout is the simplest and best. Urinometers should always be tested by placing them in distilled water at 60° Fahr. from 1·015 to 1·025 Beale.

=URN POWDER.= Crocus martis, or jeweller’s rouge.

=URTICAR′IA.= See RASH.

=US′QUEBAUGH.= _Syn._ ESCUBAC. Literally, mad water, the Irish name of which, ‘whisky,’ is a corruption. At the present time it is applied to a strong cordial spirit, much drunk in Ireland, and made in the greatest perfection at Drogheda.

_Prep._ 1. Brandy or proof spirit, 3 galls.; dates (without their kernels) and raisins, of each, bruised, 1/4 lb.; juniper berries, bruised, 1 oz.; mace and cloves, of each 3/4 oz.; coriander and aniseed, of each 1/2 oz.; cinnamon, 1/4 oz.; macerate, with frequent agitation, for 14 days, then filter, and add of capillaire or simple syrup, 1 gall.

2. Pimento and caraways, of each 3 oz.; mace, cloves, and nutmegs, of each 2 oz; aniseed, corianders, and angelica root, of each 8 oz.; raisins, stoned and bruised, 14 lbs.; proof spirit, 9 galls.; digest as before, then press, filter, or clarify, and add of simple syrup, q. s. Should it turn milky, add a little strong spirit, or clarify it with alum, or filter through magnesia.

_Obs._ Usquebaugh is either coloured yellow with saffron (about 1/4 oz. per gall.), or green with sap-green (about 1/2 oz. per gall.); either being added to the other ingredients before maceration in the spirit.

=UVA URSI.= The _Arctostaphylus Uva Ursi_ (the Bearberry) is an indigenous plant, the leaves of which are employed in medicine. Bearberry leaves contain a large percentage of tannic acid, with a small quantity of gallic acid, some resin, and a little volatile oil and extractive, together with a crystallisable principle named _arbutin_, which is said to be a very powerful diuretic. Another crystallisable resinous body named _arbutin_ has also been discovered in them. Bearberry leaves either in the form of powder, infusion, or extract, are chiefly used in chronic diseases of the bladder, in which there is an abnormal secretion of mucus, such as _catarrhus vesicæ_, but neither acute nor active inflammation.

=VACCINA′TION.= See COW-POX. (POX.)

=VAC′CINE MATTER.= _Syn._ LYMPHA VACCINIÆ, L. This is collected either upon the points of lancet-like pieces of ivory, or by opening the pustule, and applying a small glass ball and tube (like those called by the boys in London candle-pops, or fire-pops) to the orifice, expelling part of the air in the ball by bringing a lighted taper near it; then, withdrawing the taper, the matter is sucked into the ball, in which it may be sealed up hermetically or cemented, and thus kept for a length of time. It is, however, now generally preserved between two small pieces of glass, or in straight capillary glass tubes. It is said that cotton thread is a convenient and efficient vehicle. The matter may be liquefied with a little clean water before application. A degree of heat scarcely higher than that of the blood lessens its efficacy.

=VAC′UUM.= Empty space; a portion of space void of matter. For experimental and manufacturing purposes, a sufficient vacuum is produced either by means of the air-pump, or by filling an inclosed space by steam, which is then condensed by the application of cold. Evaporation proceeds much more rapidly, and liquids boil at much lower temperatures in an exhausted receiver than when exposed to the air. Thus, under ordinary circumstances, in the air, ether boils at 96°, alcohol at 177°, and Water at 212° Fahr.; but in vacuo water boils at about 88°, alcohol at 56°, and ether at -20° Fahr. In the best vacuum obtainable by a powerful air-pump, water placed over oil of vitriol, to absorb the aqueous vapour as it forms, will often enter into violent ebullition whilst ice is in the act of formation on its surface. The reduction of the boiling-point with reduced pressure is practically taken advantage of by the pharmaceutist in the preparation of extracts, by the sugar refiner in the evaporation of his syrups, by the distiller in the production of certain liqueurs, and by the chemist in a variety of processes of interest or utility. See EXTRACTS, EVAPORATION, REFRIGERATION, &c.

=VALE′′RIAN.= _Syn._ VALERIANÆ RADIX (B. P.), VALERIANÆ RADIX, VALERIANA (Ph. L. E. & D.), L. “The root of the wild plant _Valeriana officinalis_ (Linn.), or wild valerian.” (Ph. L.) An excitant, antispasmodic, tonic, and emmenagogue, not only acting on the secretions, but exercising a specific influence over the cerebro-spinal system, and in large quantities producing agitation, mental exaltation, and even intoxication.——_Dose_, 10 to 30 or 40 gr., thrice daily; in hysteria, epilepsy, headache (affecting only one side), morbid nervous sensibility, &c. Even the odour of it exerts a species of fascination over cats.

=VALERIAN′IC ACID.= HC_{5}H_{9}O_{2}. _Syn._ VALERIC ACID; ACIDUM VALERIANICUM, A. VALERICUM, L. _Prep._ 1. A mixture of potato oil or corn-spirit oil (hydrated oxide of amyl) with about 10 times its weight of quicklime and hydrate of potassa in equal proportions, placed in a glass flask, is kept heated to about 400° Fahr., for 10 or 12 hours, by means of a bath of oil or fusible metal; the nearly white solid residuum is mixed with water, an excess of sulphuric acid added to the mixture, and the whole subjected to distillation; the distillate is supersaturated with potassa, evaporated nearly to dryness, to dissipate any undecomposed potato oil, and then mixed with weak sulphuric acid in excess; a light oily liquid (terhydrated valerianic acid) separates, which by cautious rectification, yields at first water containing a little acid, and afterwards pure monohydrated valerianic acid, which is perfectly identical with that prepared from valerian root.

2. (Ph. D.) See VALERIANATE OF SODIUM. This is a most economical process.

_Prop., &c._ A limpid oily liquid, smelling strongly of valerian root; it has an acid taste and reaction, and leaves a sensation of sweetness and a white spot on the tongue; is inflammable; boils at 347°; is freely soluble in alcohol and ether; dissolves in 30 parts of water, and forms salts called valerianates, most of which have a sweetish taste, are soluble, and uncrystallisable; sp. gr. ·937; placed in contact with water, it absorbs a portion of it, and is converted into the terhydrated acid, with increase of sp. gr., and reduction of the boiling-point.

=VALE′′RIC ACID.= See VALERIANIC ACID.

=VALO′NIA.= The cup of a large species of acorn, imported from the Levant. Used in tanning leather.

=VANAD′IC ACID.= V_{2}O_{2}. _Syn._ VANADIC ANHYDRIDE, TEROXIDE OF V.; ACIDUM VANADICUM, L. _Prep._ (Johnston.) From the native vanadate of lead, by dissolving it in nitric acid, passing sulphuretted hydrogen through the solution, to throw down lead and arsenic, filtering, and evaporating the resulting blue liquid to dryness; the residuum is then dissolved in a solution of ammonia, and a piece of sal ammoniac, considerably larger than can be dissolved, introduced; as the latter dissolves, a pulverulent precipitate of vanadate of ammonium is formed, which must be washed, first in a solution of sal ammoniac, and then in alcohol of ·860; by exposing this salt, in an open platinum crucible, to a heat a little below redness, and keeping it constantly stirred, until it acquires a dark red colour, pure vanadic acid is obtained.

_Prep., &c._ Vanadic acid is orange coloured, scarcely soluble in water, and forms, with the alkaline bases, soluble salts called vanadates; and with the other bases sparingly soluble salts. All of these have an orange or yellow colour. “Vanadate of ammonia mixed with solution of galls forms a black fluid, which is the best writing ink hitherto known. The quantity of salt required for this purpose is very small; the writing is perfectly black, and not obliterated by alkalies, acids, chlorine, or other reagents,” (Ure.)

=VANA′DIUM.= V. A rare metal discovered by Sefstom, in 1830. in some Swedish iron extracted from an iron mine near Jönköping. It has since been found in a Vanadinite lead ore met with in Scotland, Zimpanan in Mexico, and Chili, and in the iron slag of Staffordshire. Of late years a more abundant source of Vanadium has been discovered by Professor Roscoe in the cupriferous stratum of the New Red Sandstone at Alderley Edge in Cheshire. There are four, and possibly five oxides of this element.

=Vanadic oxychloride.= _Syn._ VANADIC OXYTRICHLORIDE. (VOCl_{3}.) Roscoe states there are several oxychlorides of vanadium, which, however, have not been studied. The most interesting of them is the oxytrichloride, which corresponds to the phosphorous oxychloride. This oxytrichloride is a yellow fuming liquid, which is instantly decomposed by water into vanadic and hydrochloric acids. The oxytrichloride may be obtained by heating vanadic anhydride and charcoal (mixed together) in a current of hydrogen, after which it is heated in a current of dry chlorine. An easier method is by passing dry chlorine over the sesquioxide of vanadium.

=Vanadic pentoxide.= _Syn._ VANADIC ANHYDRIDE (V_{2}O_{5}.). At a red hot heat this oxide fuses, and on cooling, crystallises in rhombic prisms. It is but little soluble in water; the aqueous solution, which is of a yellow tint, is strongly acid, and produces a marked reddening effect on litmus. Vanadic anhydride forms both normal and acid salts. The ammonic vanadiate (Roscoe’s meta vanadiate) is the chief source of the acid. This salt may be obtained by adding pieces of sal ammoniac to a crude solution of potassic vanadiate, the resulting ammonic vanadiate being insoluble in a saturated solution of sal ammoniac, is deposited in small crystalline grains. The vanadic anhydride may be obtained from the ammonic vanadiate by heating an aqueous solution of the salt in the open air, when the ammonia is driven off, and the vanadic anhydride is left behind. The acid ammonic vanadiate, mixed with tincture of galls, makes a very durable writing ink, unacted upon either by alkalies or chlorine. Acids turn such blue without, however, destroying it.

=Vanadic triox′ide.= (V_{2}O_{2}.), is the _Vanadyl_ of Roscoe, who obtained it in the form of a grey metallic-looking powder, by the transmission of a current of dry hydrogen charged with the vapours of oxychloride of Vanadium, through a tube containing ignited charcoal. It dissolves in dilute acids, with evolution of hydrogen. Solutions of its salts are lavender coloured. Berzelius regarded this oxide as a metal.

_Tests._ The vanadiates mostly occur of a red or yellow colour. When treated with sulphuretted hydrogen, they yield a solution of a fine blue colour, a reaction that distinguishes them from the chromates, which, under similar treatment, would give a green liquid. When mixed with borax and exposed to the reducing flame of the blowpipe, compounds containing vanadium give a green glass, which turns to yellow in the oxidizing flame. Professor Roscoe, to whose researches we are indebted for all the chemical knowledge we possess respecting vanadium, says:——“All the main facts now established in connection with the chemical department of this element proved it to bear a strong analogy to the elements phosphorus and arsenic; in fact, it occupied a previously vacant place in a well-defined group of triad, or, as some chemists prefer to consider them, pentad elements. There was a property of vanadium in virtue of which it might ultimately obtain considerable importance in the arts, though in the present infancy of the history of the metal it was difficult to foretell this with any certainty. This property was the power of forming a permanent black for dyeing purposes. The black produced by the action of vanadium had the advantage over copper and aniline blacks, viz. that it was permanent, whereas the latter were liable to turn green. This application of an element that was first introduced into notice as a chemical curiosity furnished one more example of the importance of original scientific investigation. However far a newly discovered substance might seem to be removed from purposes of practical utility, we never know at what moment it might be turned to account for the benefit of the human race.”

=VANIL′LA.= _Syn._ VANILLE, Fr. The dried pods of various species of Vanilla, a genus of the natural order _Orchidaceæ_. It is chiefly used in the manufacture of chocolate and perfumery. As a medicine it is much employed on the Continent as an aromatic stimulant and neurotic.——_Dose_, 6 to 12 gr.; in asthenic fevers, hysteria, hypochondriasis, impotency, &c.

Vanilla is reduced to powder (PULVIS VANILLÆ; POUDRE DE VANILLE) by slicing it, and triturating the fragments with twice or thrice their weight of well-dried lump sugar. For SUCRE DE VANILLE, 11 parts of sugar are employed.

The following table given by Messrs Tieman and Harmann, in the _Journal of the Berlin Chemical Society_, represents the quantities of Vanillin (the aromatic principle of Vanilla) contained in that substance, as obtained from different sources:——

Vanillin
per Cent.

Mexican Vanilla (1873, harvest) 1·69
Mexican Vanilla (1874, harvest) 1·86
Mexican Vanilla Medium quality 1·32
Bourbon, best quality (1874-75) 1·91
Bourbon, (1874-75) 1·97
Bourbon, (1874-75) 2·90
Bourbon, Small medium (1874-75) 1·55
Java, best quality (1873) 2·75
Java, best quality (1874) 1·56

=VANILLIN.= A crystallised substance obtained from pine juice by Messrs Tiemann and Harmann. It has been shown to be identical with the aromatic principle of Vanilla.

In a paper read before the Royal Society the authors have described the process by which vanillin was artificially prepared by them. They state that the sap of the cambium of coniferous trees contains a beautiful crystalline glucoside coniferine, which was discovered by Kartig, and examined some years ago by Rubel, who arrived at the formula C_{24}H_{32}O_{12} + 3 Aq. A minute study of this compound leads us to represent the molecule of coniferine by the expression, C_{16}H_{22}O_{3} × 2 Aq., the per centages of which nearly coincide with the theoretical values of Kubel’s formula.

Submitted to fermentation with emulsine, coniferine splits into sugar, and a splendid compound, crystallising in prisms, which fuse at 73°. This body is easily soluble in ether, less so in alcohol, almost insoluble in water; its composition is represented by the formula C_{10}H_{12}O_{3}. The change is represented by the equation——

C_{16}H_{22}O_{8} + H_{2}O = C_{6}H_{12}O_{6} + C_{10}H_{12}O_{3}.

Under the influence of oxidising agents, the product of fermentation undergoes a remarkable metamorphosis. On boiling it with a mixture of potassium bichromate and sulphuric acid, there passes with the vapour of water in the first place ethylic aldehyd, and subsequently an acid compound soluble in water, from which it may be removed by ether. On evaporating the ethereal solution, crystals in stellar groups are left behind, which fuse at 81°. These crystals have the taste and odour of vanilla.

An accurate comparative examination has proved them to be identical with the crystalline substance which constitutes the aroma of vanilla, and which is often seen covering the surface of vanilla pods.

On analysis, the crystals we obtained were found to contain C_{8}H_{8}O_{3}. This is exactly the composition which recent researches of Carles have established for the aromatic principle of vanilla. The transformation of the crystalline product of fermentation into vanillin is represented by the following equation:

C_{10}H_{12}O_{3} + O = C_{2}H_{4}O + C_{8}H_{8}O_{3}.

To remove all doubt regarding the identity of artificial vanillin with the natural compound, we have transformed the former into a series of salts, which have the general formula, C_{8}H_{7}MO_{3}, and into two substitution products, C_{8}H_{7}BrO_{31}, and C_{8}H_{7}TO_{3}, both of which had previously been prepared by Carles from the natural compound.

=VAN SWIETEN’S SOLUTION.= Contains 1/1000th part of its weight of corrosive sublimate; or 1/2 gr. per fl. oz.

=VAPOUR.= Vapours are really gases, and amenable to substantially the same physical laws; as ordinarily understood, however, the difference between a gas and a vapour is the following:——A gas is a form of matter which exists, at ordinary temperatures and pressures, in a state of vapour; whilst a vapour has been formed by the application of heat to a body usually existing in the solid or liquid form; gases, therefore, differ from vapours only in being derived from bodies which, in the solid or liquid form, boil at very much lower temperatures.

=Vapour of Ammonia.= _Syn._ VAPOR AMMONIÆ. (St Th. Hosp.) Solution of ammonia (·959), water, equal parts. A teaspoonful in a pint of water at 80° F. for each inhalation. In chronic laryngitis and functional aphonia.

=Vapour of Benzoin.= _Syn._ VAPOR BENZOINI. (St Th. Hosp.) Compound tincture of benzoin, 1 oz. A teaspoonful to 1 pint of water at 140° F. In acute inflammation of the pharynx and larynx.

=Vapour of Carbolic Acid.= _Syn._ VAPOR ACIDI CARBOLICI. (St Th. Hosp.) Carbolic acid, 420 gr.; water, 1 dr.; 20 drops of this in 1 pint of water, at 140° F., for each inhalation. For syphilitic and carcinomatous ulcerations.

=Vapour of Chlorine.= _Syn._ VAPOR CHLORI. (B. P.) Put chlorinated lime, 2 oz., into a suitable apparatus, moisten it with cold water, and let the vapour that arises be inhaled.

=Vapour of Conia.= _Syn._ VAPOR CONIÆ. (B. P.) Mix extract of hemlock, 60 gr.; solution of potash, 1 dr.; and distilled water, 9 dr. Put 20 minims of the mixture on a sponge, in a suitable apparatus, that the vapour of hot water passed over it may be inhaled.

=Vapour of Creosote.= _Syn._ VAPOR CREOSOTI. (B. P.) Mix creosote, 12 minims, and boiling water, 8 oz., in an apparatus so arranged that air may be inhaled through the solution.

=Vapour of Hop.= _Syn._ VAPOR LUPULI. (St Th. Hosp.) Oil of hops, 6 minims; light carbonate of magnesia, 10 gr.; water, 1 oz. A teaspoonful in 1 pint of water, at 140° F., for each inhalation. Sedative.

=Vapour of Hydrocyanic Acid.= _Syn._ VAPOR ACIDI HYDROCYANICI. (B. P.) Mix from 10 to 15 minims of diluted hydrocyanic acid with 1 dr. of cold water in a suitable apparatus, and let the vapour that arises be inhaled.

=Vapour of Iodine.= _Syn._ VAPOR IODI. Mix tincture of iodine, 1 fl. dr., and water, 1 oz., and, having applied a gentle heat, let the vapour that arises be inhaled.

=Vapour of Lactic Acid.= _Syn._ VAPOR ACIDI LACTICI. (St Th. Hosp.) Lactic acid, 20 minims; distilled water, 1 oz.; mix. For spray inhalation. Dissolves the membranous exudation in diphtheria,

=Vapour of Oil of Juniper.= _Syn._ VAPOR OLEI JUNIPERI. (St Th. Hosp.) English oil of juniper, 20 minims; light carbonate of magnesia, 10 gr.; water, 1 oz. A teaspoonful to 1 pint of water at 140° F. for each inhalation. For vocal weakness.

=Vapour of Oil of Mountain Pine.= _Syn._ VAPOR PINI PLUMILIONIS. (St Th. Hosp.) Oil of mountain pine, 1/2 dr.; light carbonate of magnesia, 15 gr.; water, 1 oz.; 1 dr. to 1 pint of water at 140° F. for each inhalation. In chronic laryngitis.

=Vapour of Oil of Myrtle.= _Syn._ VAPOR OLEI MYRTI. (St Th. Hosp.) Oil of myrtle, 6 minims; light carbonate of magnesia, 6 gr.; water, 1 oz. A teaspoonful in a pint of water at 140° F. for each inhalation. In acute tonsillitis.

=Vapour of Nitrite of Amyl.= _Syn._ VAPOR AMYL NITRITIS. (St Th. Hosp.) Nitrite of amyl, 8 minims; rectified spirit, 1 oz. A teaspoonful in a pint of water at 100° F. for each inhalation. In asthma and spasm of the glottis.

=Vapour of Scotch Pine.= _Syn._ VAPOR PINI SYLVESTRIS. Oil of Scotch pine (fir-wood oil), 40 minims; light carbonate of magnesia, 20 gr.; water, 1 oz.; 1 dr. to 1 pint of water at 140° F. for each inhalation. In chronic laryngitis.

=Vapour of Sulphurous Acid.= _Syn._ VAPOR ACIDI SULPHUROSI. (St Th. Hosp.) Sulphurous acid, 15 minims; water, 1 oz. For spray inhalation. Stimulant and antiseptic.

=Vapour of Thymol.= _Syn._ VAPOR THYMOLIS. Thymol, 6 gr.; rectified spirit, 1 dr.; light carbonate of magnesia, 3 gr.; water, 1 oz. 1 dr. to 1 pint of water at 140° F. for each inhalation. In pharyngitis and laryngitis when associated with exanthemata.

=VARICOSE VEINS.= See VARIX.

=VARIX.= The permanent unequal dilation of a vein or veins, which are then said to be ‘varicose.’ It is known by the presence of a soft tumour, which does not pulsate, and often assumes a serpentine figure. Varicose veins of the groin and scrotum generally form a collection of knots. The treatment consists of cold applications, and pressure from bandages. Some cases are relieved by ligature. When occurring in the legs, much standing or walking should be avoided, and the use of the elastic stockings made for the purpose will be proper.

=VAR′NISH.= _Syn._ VERNIS, Fr. Any liquid matter, which, when applied to the surface of a solid body, becomes dry, and forms a hard glossy coating, impervious to air and moisture.

Varnishes are commonly divided into two classes——FAT or OIL VARNISHES and SPIRIT VARNISHES. The fixed or volatile oils, or mixtures of them, are used as vehicles or solvents in the former, and concentrated alcohol in the latter.[254] The sp. gr. of alcohol for the purpose of making varnishes should not be more than ·8156 (= 67 o. p.), and it should be preferably chosen of even greater strength. A little camphor is often dissolved in it, to increase its solvent power. The oil of turpentine, which is the essential oil chiefly employed for varnishes, should be pure and colourless. Pale drying linseed oil is the fixed oil generally used; but poppy oil and nut oil are also occasionally employed. Among the substances which are dissolved in the above menstrua are——amber, animé, copal, elemi, lac, mastic, and sandarach, to impart body and lustre; benzoin, on account of its agreeable odour; annotta, gamboge, saffron, socotrine aloes, and turmeric, to give a yellow colour; dragon’s blood and red sandal wood, to give a red tinge; asphaltum, to give a black colour and body; and caoutchouc to impart toughness and elasticity.

[Footnote 254: Methylated spirit is now generally used for making spirit varnishes, in place of duty-paid alcohol.]

In the preparation of spirit varnishes care should be taken to prevent the evaporation of the alcohol as much as possible, and also to preserve the portion that evaporates. On the large scale, a common still may be advantageously employed; the head being furnished with a stuffing-box, to permit of the passage of a vertical rod, connected with a stirrer at one end and a working handle at the other. The gum and spirit being introduced, the head of the still closely fitted on and luted, and the connection made with a proper refrigerator, heat (preferably that of steam or a water bath) should be applied, and the spirit brought to a gentle boil, after which it should be partially withdrawn, and agitation continued until the gum is dissolved. The spirit which has distilled over should be then added to the varnish, and after thorough admixture the whole should be run off, as rapidly as possible, through a silk-gauze sieve, into stone jars, which should be immediately corked down, and set aside to clarify. On the small scale, spirit varnishes are best made by maceration in closed bottles or tin cans, either in the cold or by the heat of a water bath. In order to prevent the agglutination of the resin, it is often advantageously mixed with clean siliceous sand or pounded glass, by which the surface is much increased, and the solvent power of the menstruum greatly promoted.

To ensure the excellence of oil varnishes, one of the most important points is the use of good drying oil. Linseed oil for this purpose should be very pale, perfectly limpid or transparent, scarcely odorous, and mellow and sweet to the taste.——100 galls. of such an oil is put into an iron or copper boiler, capable of holding fully 150 galls., gradually heated to a gentle simmer, and kept near that point for about 2 hours, to expel moisture; the scum is then carefully removed, and 14 lbs. of finely pulverised scale litharge, 12 lbs. of red lead, and 8 lbs. of powdered umber (all carefully dried and free from moisture), are gradually sprinkled in; the whole is then kept well stirred, to prevent the driers sinking to the bottom, and the boiling is continued at a gentle heat for about 3 hours longer; the fire is next withdrawn, and, after 30 to 40 hours’ repose, the scum is carefully removed, and the clear supernatant oil decanted from the ‘bottoms,’——The product forms the best boiled or drying oil of the varnish maker.——Another method is to heat a hogshead of the oil gradually for 2 hours, then to gently simmer it for about 3 hours longer, and, after removing the scum, to add, gradually, 1 lb. of the best calcined magnesia, observing to mix it up well with the oil, and, afterwards to continue the boiling pretty briskly for at least an hour, with constant agitation. The fire is then allowed to die away, and, after 24 hours, the oil is decanted as before. The product is called ‘clarified oil,’ and requires to be used with driers. It should be allowed to lay in the cistern for 2 or 3 months to clarify.

In the preparation of oil varnishes, the gum is melted as rapidly as possible, without discolouring or burning it; and when completely fused, the oil, also heated to nearly the boiling point, is poured in, after which the mixture is boiled until it appears perfectly homogeneous and clear, like oil, when the heat is raised, the driers (if any are to be used) gradually and cautiously sprinkled in, and the boiling continued, with constant stirring, for 3 or 4 hours, or until a little, when cooled on a palette knife, feels strong and stringy between the fingers. The mixture is next allowed to cool considerably, but while still quite fluid, the turpentine, previously made moderately hot, is cautiously added, and the whole thoroughly incorporated. The varnish is then run through a filter or sieve into stone jars, cans, or other vessels, and set aside to clarify itself by subsidence. When no driers are used, the mixture of oil and gum is boiled until it runs perfectly clear, when it is removed from the fire, and, after it has cooled a little, the turpentine is added as before.

It is generally conceived that the more perfectly the gum is fused, or run, as it is called, the larger and stronger will be the product; and the longer the boiling of the ‘gum’ and oil is continued, within moderation, the freer the resulting varnish will work and cover. An excess of heat renders the varnish stringy, and injures its flowing qualities. For pale varnishes as little heat as possible should be employed throughout the whole process. Good body varnishes should contain 1-1/2 lb.; carriage, wainscot, and mahogany varnish, fully 1 lb.; and gold size and black japan, fully 1/2 lb. of gum per gall., besides the asphaltum in the latter. Spirit varnishes should contain about 2-1/2 lbs. of gum per gall. The use of too much driers is found to injure the brilliancy and transparency of the varnish. Copperas does not combine with varnish, but only hardens it; sugar of lead, however, dissolves in it to a greater or less extent. Boiling oil of turpentine combines very readily with melted copal, and it is an improvement on the common process, to use it either before or in conjunction with the oil, in the preparation of copal varnish that it is desired should be very white. Gums of difficult solubility are rendered more soluble by being exposed, in the state of powder, for some time to the air.

Varnishes, like wines, improve by age; and should always be kept as long as possible before use.

From the inflammable nature of the materials of which varnishes are composed, their manufacture should be only carried on in some detached building of little value, and built of uninflammable materials. When a pot of varnish, gum, or turpentine catches fire, it is most readily extinguished by closely covering it with a piece of stout woollen carpeting, which should be always kept at hand, ready for the purpose.

An excellent paper, by Mr J. W. Niel, on the manufacture of varnishes, will be found in the ‘Trans. of the Soc. of Arts,’ vol. xlix. See also the articles ALCOHOL, AMBER, COPAL, OILS, &c., in this work.

=Varnish, Am′ber.= _Prep._ 1. Take of amber (clear and pale), 6 lbs.; fuse it, add of hot clarified linseed oil, 2 galls.; boil until it ‘strings well,’ then let it cool a little, and add of oil of turpentine 4 galls, or q. s. Nearly as pale as copal varnish; it soon becomes very hard, and is the most durable of the oil varnishes; but it requires some time before it is fit for polishing, unless the articles are ‘stoved.’ When required to dry and harden quicker, drying oil may be substituted for the linseed oil, or ‘driers’ may be added during the boiling.

2. Amber, 4 oz.; pale boiled oil, 1 quart; proceed as last. Very hard.

3. Pale transparent amber, 5 oz.; clarified linseed oil or pale boiled oil, and oil of turpentine, of each 1 pint; as before.

_Obs._ Amber varnish is suited for all purposes where a very hard and durable oil varnish is required. The paler kind is superior to copal varnish, and is often mixed with the latter to increase its hardness and durability. The only objection to it is the difficulty of preparing it of a very pale colour. It may, however, be easily bleached with some fresh-slaked lime.

=Varnish, Balloon.= See VARNISH, FLEXIBLE (_below_).

=Varnish, Bessemer’s.= This consists of a pale oil copal varnish, diluted with about 6 times its volume of oil of turpentine, the mixture being subsequently agitated with about 1-30th part of dry slaked lime, and decanted after a few days’ repose. Five parts of the product mixed with 4 parts of bronze powder forms ‘Bessemer’s gold paint.’

=Varnish, Black.= _Prep._ 1. (BLACK AMBER VARNISH.) From amber, 1 lb.; fuse, add, of hot drying oil, 1/2 pint; powdered black resin, 3 oz.; asphaltum (Naples), 4 oz.; when properly incorporated and considerably cooled, add of oil of turpentine, 1 pint. This is the beautiful black varnish of the coachmakers.

2. (IRONWORK BLACK.) From asphaltum, 48 lbs.; fuse, add of boiled oil, 10 galls.; red lead and litharge, of each 7 lbs.; dried and powdered white copperas, 3 lbs.; boil for 2 hours, then add of dark gum amber (fused), 8 lbs.; hot linseed oil, 2 galls.; boil for 2 hours longer, or until a little of the mass, when cooled, may be rolled into pills, then withdraw the heat, and afterwards thin it down with oil of turpentine, 30 galls. Used for the ironwork of carriages, and other nice purposes.

(3. BLACK JAPAN, BITUMINOUS VARNISH.)——_a._ From Naples asphaltum, 50 lbs.; dark gum animé, 8 lbs.; fuse, add of linseed oil, 12 galls.; boil as before, then add of dark gum amber, 10 lb., previously fused and boiled with linseed oil, 2 galls.; next add of driers q. s., and further proceed as ordered in No. 2. Excellent for either wood or metals.

_b._ From burnt umber, 8 oz.; true asphaltum, 4 oz.; boiled linseed oil, 1 gall.; grind the umber with a little of the oil; add it to the asphaltum, previously dissolved in a small quantity of the oil by heat; mix, add the remainder of the oil, boil, cool, and thin with a sufficient quantity of oil of turpentine. Flexible.

4. (BRUNSWICK BLACK.)——_a._ To asphalt, 2 lbs., fused in an iron pot, add of hot boiled oil, 1 pint; mix well, remove the pot from the fire, and, when cooled a little, add of oil of turpentine, 2 quarts. Used to blacken and polish grates and ironwork. Some makers add driers.

_b._ From black pitch and gas-tar asphaltum, of each 25 lbs.; boil gently for 5 hours, then add, of linseed oil, 8 galls.; litharge and red lead, of each 10 lbs.; boil as before, and thin with oil of turpentine, 20 galls. Inferior to the last, but cheaper.

=Varnish, Body.= _Prep._ 1. From the finest African copal, 8 lbs.; drying oil, 2 galls.; oil of turpentine, 3-1/2 galls.; proceed as for AMBER VARNISH. Very hard and durable.

2. Pale gum copal, 8 lbs.; clarified oil, 2 galls.; dried sugar of lead, 1/2 lb.; oil of turpentine, 3-1/2 galls.; proceed as before, and mix the product, whilst still hot, with the following varnish:——Pale gum animé, 8 lbs.; linseed oil, 2 galls.; dried white copperas, 1/4 lb.; oil of turpentine, 3-1/2 galls.; the mixed varnishes are to be immediately strained into the cans or cistern. Dries in about 6 hours in winter, and in about 4 hours in summer. Used for the bodies of coaches and other vehicles.

=Varnish, Bookbinder’s.= _Prep._ Take of pale gum sandarach, 3 oz.; rectified spirit, 1 pint; dissolve by cold digestion and frequent agitation. Used by binders to varnish morocco leather book-covers. A similar varnish is also prepared from very pale shell-lac and wood naphtha.

=Varnish for Boots and Shoes.= See BOOTS and SHOES.

=Varnish, Cabinet-maker’s.= French polish is occasionally so called.

=Varnish, Carriage.= _Prep._ 1. (SPIRIT.) Take of gum sandarach, 1-1/4 lb.; very pale shell-lac, 3/4 lb.; very pale transparent resin, 1/2 lb.; rectified spirit of ·8221 (64 o. p.), 3 quarts; dissolve, and add of pure Canadian balsam, 1-1/2 lb. Used for the internal parts of carriages, &c. Dries in 10 minutes or less.

2. (OIL.)——_a._ (Best pale.) Take of pale African copal, 8 lbs.; fuse, add of clarified linseed oil, 2-1/2 galls.; boil until very stringy, then add of dried copperas and litharge, of each 1/4 lb.; again boil, thin with oil of turpentine, 5-1/2 galls.; mix, whilst both are hot with the following varnish, and immediately strain the mixture into a covered vessel:——Gum animé, 8 lbs.; clarified linseed oil, 2-1/2 galls.; dried sugar of lead and litharge, of each 1/4 lb.; boil as before, thin with oil of turpentine, 5-1/2 galls. Dries in 4 hours in summer, and 6 in winter. Used for the wheels, springs, and carriage parts of coaches, and other vehicles, and by house painters, decorators, &c., who want a strong, quick-drying, and durable varnish.

_b._ (Second quality.) From gum animé (‘sorts’), 8 lbs.; clarified oil, 3 galls.; litharge, 5 oz.; dried and powdered sugar of lead and white copperas, of each 4 oz.; boil as last, and thin with oil of turpentine, 5-1/2 galls. Used as the last.

=Varnish, Chinese.= _Prep._ From mastic and sandarach, of each 2 oz.; rectified spirit (64 o. p.), 1 pint; dissolve. Dries in 6 minutes. Very tough and brilliant.

=Varnish, Copal.= _Prep._ 1. (OIL.)——_a._ From pale hard copal, 2 lbs.; fuse, add of hot drying oil, 1 pint; boil as before directed, and thin with oil of turpentine, 3 pints, or q. s. Dries hard in 12 to 24 hours.

_b._ From clear and pale African copal, 8 lbs.; pale drying oil, 2 galls.; rectified oil of turpentine, 3 galls.; proceed as before and immediately strain it into the store can or cistern. Very fine, hard, and durable.

2. (SPIRIT.)——_a._ From coarsely powdered copal and glass, of each 4 oz.; alcohol of 90% (64 o. p.), 1 pint; camphor, 1/2 oz.; heat the mixture, with frequent stirring, in a water bath, so that the bubbles may be counted as they rise until solution is complete, and, when cold, decant the clear portion.

_b._ From copal (which has been melted, dropped into water, and then dried and powdered), 4 oz.; gum sandarach, 6 oz.; mastic, 2 oz.; pure Chio turpentine, 3 oz.; powdered glass, 5 oz.; spirit of 90%, 1 quart; dissolve by a gentle heat. Dries rapidly.

3. (TURPENTINE.) To oil of turpentine, 1 pint, heated in a water bath, add in small portions at a time, of powdered copal (prepared as above), 3 to 4 oz.; dissolve, &c., as before. Dries slowly, but is very pale and durable.

4. (JAPANNER’S COPAL VARNISH.) From pale African copal, 7 lbs.; pale drying oil, 1/2 gall.; oil of turpentine, 3 galls.; proceed as in No. 1. Dries in 20 to 60 minutes, and may be polished as soon as hard, particularly if stoved. See JAPANNING.

_Obs._ All copal varnishes, when properly made, are very hard and durable, though less so than those of amber; but they have the advantage over the latter of being paler. They are applied on coaches, pictures, polished metal, wood, and other objects requiring a good durable varnish. Animé is frequently substituted for copal in the copal varnishes of the shops. See VARNISHES, BODY, CARRIAGE, and COPAL, &c.

=Varnish, Crystal.= _Prep._ 1. From genuine pale Canada balsam and rectified oil of turpentine, equal parts. Used for maps, prints, drawings, and other articles of paper, and also to prepare tracing paper, and to transfer engravings.

2. Mastic, 3 oz.; rectified spirit, 1 pint; dissolve. Used to fix pencil drawings.

=Varnish, Drying.= Spirit copal varnish.

=Varnish, Dutch.= Lac and toy varnishes are often so called.

=Varnish, Etch′ing.= See ETCHING.

=Varnish, Fat.= See OIL VARNISH.

=Varnish, Flexible.= _Syn._ BALLOON VARNISH, CAOUTCHOUC V., INDIA-RUBBER V. _Prep._ 1. From india rubber (cut small), 1-1/2 oz.; chloroform, ether (washed), or bisulphuret of carbon, 1 pint; digest in the cold until solution is complete. Dries as soon as it is laid on. Pure gutta percha may be substituted for india rubber.

2. India rubber, in shavings, 1 oz.; rectified mineral naphtha or benzol. 1 pint; digest at a gentle heat in a closed vessel, and strain. Dries very badly, and never gets perfectly hard.

3. India rubber, 1 oz.; drying oil, 1 quart; dissolve by heat. Very tough; dries in about 48 hours.

4. Linseed oil, 1 gall.; dried white copperas and sugar of lead, of each 3 oz.; litharge, 8 oz.; boil, with constant agitation, until it strings well, then cool slowly, and decant the clear portion. If too thick, thin it down with quick-drying linseed oil. The above are used for balloons, gas bags, &c. See BALLOON, CAOUTCHOUC, &c.