Cooley's Cyclopædia of Practical Receipts and Collateral Information in the Arts, Manufactures, Professions, and Trades..., Sixth Edition, Volume I

Chapter II: Deposition of the Precious Metals (7)

Text size

Messrs Lawes and Gilbert estimate the manurial value of the urine and fæces together at 6s. 8d. per annum for every individual, which corresponds to a yearly produce of about 10 lbs. of ammonia; but Messrs Hoffman, Witt, and Thudichum assess it at 8s. 6d. for a mixed population of both sexes and of all ages, which they say represents about 13 lbs. of ammonia.

Fæcal matter decomposes much more rapidly when mixed with urine than it would otherwise do, ammonia and fetid gases being given off in considerable quantities. Should much water be also present, and the temperature moderately high, light carburetted hydrogen, carbonic anhydride, nitrogen, and sulphuretted hydrogen are likewise evolved.

Unless human excreta be effectually as well as speedily removed from the dwellings, streets, &c., of a community, that community will assuredly pay the penalty of their neglect in the shape of health seriously endangered and deteriorated. If this be so with healthy evacuations, the peril becomes considerably intensified when the excreta are discharged by patients labouring under contagious or many other diseases. See URINE, SEWAGE.

=EX'ERCISE= is essential to the healthy performance of the functions of both body and mind. Without it, the stomach acts feebly, the bowels become inactive, and the circulation of the blood languid and imperfect; the chest contracts, the respiration becomes impeded, the brain is insufficiently supplied with pure arterial blood, the mind grows lethargic, the complexion assumes a sickly and effeminate hue, and the features generally lack the energy and expression which they possess in perfect health. With exercise, the bodily functions are performed with vigour and regularity, the constitution is thereby strengthened, and the attacks of disease repelled. By exercise the mind too is excited to healthy action, its gloomy reveries are dispelled, and the fair face of creation is presented to the mind's eye in its proper hues. It robs undue mental exertion of half its injurious effects upon the body, whilst it stimulates and directs it in its proper course. It improves the temper, and humanises the character. The disposition is refined, the passions restrained, violent emotions checked, the habits improved, and the personal charms promoted under the stimulus of judicious exercise.

To females, bodily exercise is even more necessary than to males. The disposition and education of females are such as tend to produce habits of sloth and indolence to a greater degree than in the other sex. Hence to them exercise is doubly important--it is inseparable from health. The more retiring dispositions of females lead them almost unconsciously into habits of inactivity, which, above all, they should endeavour to shake off and avoid. By so doing--by replacing habits of indolence and inactivity by liveliness and moderate exercise, the development of the body will be promoted, additional grace and elegance imparted to its natural movements, and the enjoyments arising from both mental and bodily health increased, whilst disease and deformity will be prevented by the removal of their cause.

The necessity of exercise exists equally in every grade of society and age of life. Those who are engaged in sedentary employments or in-door occupations, should particularly seek refreshing out-door exercise during the periods of relaxation from their diurnal duties. To the studious and delicate of both sexes, this is absolutely necessary to preserve the health and vigour of the body.

In infancy, exercise of a suitable kind should be almost the constant occupation of the little beings that claim our protection and care. It should, however, be always borne in mind, that the muscular exercise of very young children must be of the gentlest class. Prejudice and ignorance frequently induce nurses and parents to teach their children to walk, as they falsely call it, and thus their feeble limbs are urged to make premature efforts to totter along, before the bones and muscles have acquired sufficient strength to support the body in an erect position. From this course the legs and joints frequently become bent and misshapened, and severe injuries are often inflicted on the head and body by blows and falls. It should never be forgotten, that crawling and rolling are their first modes of progression, and require the least exertion. Next comes the sitting posture; from this the child gradually advances to the erect one; then to walk by slight assistance; and, lastly, to walk safely alone. All this should come naturally, and never be promoted, further than by laying the infant on the carpet or floor, for the full exercise of its little strength. As soon as a healthy child is able to walk instead of crawl, its own disposition induces it to do so. The faculty of imitation, the spirit of enterprise, and the pride of doing what others do, present even in infancy, is rather apt to lead the infant to over-exertion than the contrary. The practice of constantly 'dolling' children in the arms is most prejudicial to the early development of their feeble powers.

It is injudicious to take an infant out during the hottest part of the day in summer; such a proceeding tends to enervate and depress, rather than to strengthen him. Whenever he goes out his head should be protected from the direct rays of the sun by means of a large brimmed hat made of cotton or straw and an umbrella. The neglect of these precautions frequently gives rise to the disordered stomach, sickness, and diarrh[oe]a, so prevalent during very hot weather. During other periods of the day, the weather being favorable and the locality healthy, an infant cannot be too much out of doors, especially during teething.

Infants of three or four months' old may, under certain precautions, be sent out into the open air during the winter. They must be well wrapped up; they should be carried in the nurse's arms, and not consigned to a perambulator; they should never go out in foggy nor wet weather; if the wind be neither in the east nor the north-east there will be no objection to their being sent out on a clear frosty day. Spring is a trying period for infants and children, because of the prevalence of east winds; hence the necessity of seeing that they are well and warmly clad when sent out during this season. There is much less danger of a child taking cold during the autumn than the spring, as in autumn the winds frequently blow from the south, or warm quarter.

In childhood the exercise should be regulated according to constitution and age; avoiding inactivity, on the one hand, and excessive exercise on the other. The out-door plays and pastimes of BOYS will generally be found sufficient, and in some cases will even require to be curbed, to prevent fatigue and the overtasking of the young frame. With girls it is frequently difficult to find sufficient exercise without trespassing on the prejudices of the ignorant, or the routine of their daily education. With them walking, and some healthy amusement, as skipping, hooping, or the like, should be indulged in for some hours daily. When this is impossible or inconvenient, they may be habituated to the practice of the more simply and cleanly portion of the domestic duties. In the performance of the latter, the health will be promoted, whilst the care and attention which is always due by a female to herself and others, at all periods of her life, will become an easy acquisition, and assist the cultivation of the best feelings of her nature.

In youth exercise matures and promotes the development of the frame; and in manhood it is equally necessary, as already noticed, to keep it in healthy action. In age it will be found to assist the vital functions, and put off decay. In fact, to all--young, old, rich, and poor, physical exercise is essential to the permanent enjoyment of health.

In a medical point of view, "exercise, employed moderately, has a tonic and stimulating influence on the system, and is calculated to prove beneficial in a great variety of complaints. Used immoderately, it exhausts both the mental and bodily powers, and produces great debility." (Pereira.) Well-directed exercise favours the preservation of the general health, by calling into direct action the majority of the organs of the body; and it also acts powerfully on the skin, by stimulating its functions, increasing its temperature, awakening its tone, and subjecting it to a current of atmosphere favorable to its respiratory offices. But to be beneficial in the highest degree, exercise must be accompanied by feelings of present interest and enjoyment. The mind must direct and go with it; to ensure its full benefits, the "soul must be present."

"During convalescence, properly regulated exertion is highly serviceable; but it should never be carried so far as to produce exhaustion, and should be pursued for some time in doors, before it be attempted in the open air; the latter, at first, should always take place in a carriage, that can be opened or closed at will; the patient may then attempt short walks in the open air; but, in all cases, it is of importance that he is not unduly fatigued, as, otherwise, injury instead of benefit will be the result. One of the most serious errors, committed with regard to exertion, is that of permitting a convalescent to sit up too frequently, or for too long a time, under the mistaken notion of giving him strength. A patient should never be allowed to sit up longer than is agreeable to his feelings, and never so long as to produce a sense of fatigue." (Dr R. E. Griffith.)

The physiological effects of exercise have been studied by numerous scientific observers. The carefully conducted experiments of Dr Edward Smith have satisfactorily demonstrated that during bodily exertion the circulation of the blood through the lungs is much increased in velocity, that these latter inspire air and eliminate carbonic anhydride in quantities proportionate to the exercise taken, and that these quantities show an enormous increase over the amounts of these gases inhaled and exhaled during a state of rest.

Adopting the recumbent position as unity, Dr Edward Smith has given the following table, illustrating the quantities of air inhaled during various forms of exercise:

Lying position 1·
Sitting 1·18
Standing 1·33
Singing 1·26
Walking 1 mile per hour 1·90
Walking 2 miles per hour 2·76
Walking 3 miles per hour 3·22
Walking and carrying 34 lbs. 3·50
Walking and carrying 62 lbs. 3·84
Walking and carrying 118 lbs. 4·75
Walking at 4 miles per hour 5·
Walking at 6 miles per hour 7·
Riding and trotting 4·05
Swimming 4·33
Treadmill 5·50

Since a man takes into his lungs 480 cubic inches of air per minute, in walking four miles an hour he draws in 2400 cubic inches, and if six miles 3260 cubic inches a minute.[289]

[Footnote 289: Parkes.]

Dr Smith estimated the amount of carbonic anhydride evolved under differing conditions, and found that--

Carbonic acid exhaled
per minute in grains.
During sleep 4·99
Lying down, and almost
asleep (average of three
observations) 5·91
Walking at the rate of 2
miles an hour 18·10
Walking at the rate of 3
miles an hour 25·83
Working at the treadmill,
ascending at the rate of
26·65 feet per minute (average
of three observations) 44·97

The relative amounts of carbonic anhydride eliminated from the lungs during periods of rest and exercise have also been investigated by Pettenkofer and Voit. The following table, which gives the results of their experiments, also records the quantities of oxygen absorbed, and of water and urea excreted at the same time:--

-----------------------------------------------------------
| | Elimination in Grammes of-- |
|Absorption|------------------------------|
|of Oxygen | | | |
| in |Carbonic| Water. | Urea. |
|Grammes. | Acid. | | |
|-----------------------------------------|
Rest-day. | 708·9 | 911·5 | 828·0 | 37·2 |
Work-day. | 954·5 | 1284·2 | 2042·1 | 37·0 |
| | | | |
Excess on | } | | | |
work-day | } | | | |
(with exception| } 246·6 | 372·7 | 1214·1 | 0·2 |
of urea) | } | | | |
-----------------------------------------------------------

If the quantities in the above table be converted into ounces it will be found that nearly 8-3/4 oz. more oxygen were absorbed and 13 oz. more of carbonic anhydride eliminated by the lungs during a work-day than during a rest-day.[290] It must be stated that during the work-day an interval of rest was taken, and that the labour was by no means excessive.

[Footnote 290: Parkes.]

Hirn and Speck appear to have conclusively proved that the formation of the carbonic anhydride occurs in the muscles, and that it is rapidly carried off from them. In short, this latter result seems essential for the development of muscular energy. At any rate it is found that if the respiratory movements be in any way interfered with during exercise, and the elimination of carbonic anhydride in any degree checked, the muscular power rapidly diminishes.

An examination of Pettenkofer and Voit's table shows that exercise gives rise to the escape of a large amount of water from the body, and to a slightly diminished quantity of urea.

Since the accumulation of the superfluous carbon supplied by the food gives rise to morbid and diseased states of the body,[291] we shall now be enabled to understand why deficient exercise should be a source of physical ill-being, and why, on the contrary, the proper use of the muscles should be so essential a condition for the maintenance of health, since it is in them that the great formation of the eliminated carbon is effected. We shall also not fail to see why, since during exercise the excretion of water is so largely increased, the blood necessarily becomes less diluted and richer in quantity.

[Footnote 291: "Deficient exercise is one of the causes which produce those nutritional alterations in the lung which we class as tuberculosis."--PARKES.]

Whilst insufficiency of exercise gives rise to a weak action of the heart, and very frequently to fatty degeneration of that organ, exercise that is not excessive, although it increases the beats of the heart from ten to thirty beyond this acceleration, and imparting greater force to the pulsations, does not interfere with their regularity. Furthermore, muscular exercise, by considerably augmenting the flow of the blood through the whole body, the heart included, exercises a most beneficial function, "since it causes in all organs a more rapid outflow of plasma and absorption--in other words, a quicker renewal. In this way also it removes the products of their action, which accumulate in organs, and restores the power of action to various parts of the body."[292]

[Footnote 292: Parkes.]

Palpitation, enlargement, and valvular disease of the heart result from excessive or injudicious exercise. Wherever, therefore, fatigue or embarrassment of the heart shows itself rest must be had recourse to. Persons having weak hearts suffer greatly in ascending mountain or other heights.

The effect of exercise upon the kidneys is to diminish the quantity of water, as well as the chloride of sodium and other chlorides in the urine. As we have seen, the urea is very slightly lower; but after much exertion the uric acid is increased. There is also a slight increase in the amounts of sulphates and carbonic anhydride. Parkes could find no alteration in the phosphates. The diminution of water and the chlorides is due to the excretion of these by the skin, the function of which is greatly augmented by exercise. No urea escapes by the skin, but many acids (probably fatty ones) are liberated by that organ. Speck has shown that during exercise the amount of fluid is nearly double what it is when the body is quiescent.

This escape of fluid by perspiration doubtless affords an explanation of a diminution in the quantity of the excreta from the bowels. The fæces exhibit no decrease in nitrogen.

Exercise increases the growth of the muscles, making them at the same time harder, and also causing them to obey more readily the behests of the will. Prolonged or excessive exertion, without sufficient rest, has been found to interfere with their nutrition, and to cause them to become soft.

There is a tolerably general impression that much exercise tends to cripple the development of the mental faculties, and this idea is said to have received support from the circumstance that the athletes at our universities seldom signalise themselves in contests of learning. But this fact, it has been suggested, may be explained by the athletic exercise being indulged in to such an extent as to leave no time for cultivating the mind. If an illustration were required to prove that great bodily energy is quite consonant with mental vigour it might be found in the life of the late Professor Wilson, of Edinburgh. On this point Dr Parkes says: "Considering that perfect nutrition is not possible except with bodily activity, we should infer that sufficient exercise would be necessary for the perfect performance of mental work."

As regards the changes that take place in the muscles during exercise Dr Parkes writes: "The chief changes that take place in the muscles during action appear to be these: there is a considerable increase of temperature (Helmholtz), which, up to a certain point, is proportioned to the amount of work; it is also proportioned to the kind, being less when the muscle is allowed to shorten than if prevented from shortening (Heidenhain); the neutral or alkaline reaction of the tranquil muscle becomes acid from para-lactic acid and acid potassium phosphate; the venous blood passing from the muscles becomes much darker in colour, is much less rich in oxygen, and contains much more carbonic acid (Sczelkow); the extractive matters soluble in water lessen, those soluble in alcohol increase (Helmholtz, in frogs); the amount of water increases (in tetanus, J. Ranke), and the blood is consequently poorer in water; the amount of albumen in tetanus is less, according to Ranke, but Kühne has pointed out that the numbers do not justify the inference."

Liebig stated that the creatin is increased (but this was an inference from old observations on the extractum carnis of hunted animals, and requires confirmation). Sarokin has stated the same fact in respect to the frog. The electro-motor currents show a decided diminution during contraction.

That great molecular changes go on in the contracting muscles is certain, but their exact nature is not clear; according to Ludimar Hermann there is a jelly-like separation and coagulation of the myosin, and then a resumption of its prior form, so that there is a continual splitting of the muscular structure into a myosin coagulum, carbonic acid, and a free acid, and this constitutes the main molecular movement. But no direct evidence has been given of this.

The increased heat, the great amount of carbonic acid, and the disappearance of oxygen, combined with the respiratory phenomena already noted, all seem to show that an active oxidation goes on; and it is very probable that this is the source of the muscular action. The oxidation may be conceived to take place in two ways--either during rest oxygen is absorbed and stored up in the muscles, and gradually acts there, producing a substance which, when the muscle contracts, splits up into lactic acid, carbonic acid, &c.; or, on the other hand, during the contraction an increased absorption of oxygen goes on in the blood, and acts on the muscles, or on the substances in the blood circulating through the muscles. The first view is strengthened by some of Pettenkofer and Voit's experiments, which show that during rest a certain amount of storage of oxygen goes on, which no doubt in part occurs in the muscles themselves.

Indeed, it has been inferred that it is this stored-up oxygen, and not that breathed in at the time, which is used in muscular action. The increased oxidation gives us a reason why the nitrogenous food must be increased during periods of great exertion.

An increase in the supply of oxygen is a necessity for increased muscular action; but Pettenkofer and Voit's observations have shown that the absorption of oxygen is dependent on the amount and action of the nitrogenous structures of the body, so that, as a matter of course, if more oxygen is required for increased muscular work, more nitrogenous food is necessary. But, apart from this, although experiments on the amount of nitrogenous elimination show no very great change on the whole, there is no doubt that, with constant regular exercise, a muscle enlarges, becomes thicker, heavier, contains more solid matter, and, in fact, has gained in nitrogen. This process may be slow, but it is certain; and the nitrogen must either be supplied by increased food, or be taken from other parts.

So that, although we do not know the exact changes going on in the muscles, it is regarded as certain that regular exercise produces in them an addition of nitrogenous tissue.

Whether this addition occurs, as usually believed, in the period of rest succeeding action, when in some unexplained way the destruction which it is presumed has taken place is not only repaired, but is exceeded (a process difficult to understand), or whether the addition of nitrogen is actually made during the action of the muscle, must be left undecided for the present.

The substances which are thus oxidised in the muscle or in the blood circulating through it, and from which the energy manifested as heat or muscular movement is believed to be derived, may probably be of different kinds. Under ordinary circumstances the experiments of Fick and Wislicenus and others, and the arguments of Traube, seem sufficient to show that the non-nitrogenous substances, and perhaps especially the fats, furnish the chief substances acted upon. But it is probable that the nitrogenous substances also furnish a contingent of force. The exact mode in which the energy thus liberated by oxidation is made to assume the form of mechanical motion is quite obscure.

There seems little doubt that the exhaustion of muscles is chiefly owing to two causes--first and principally to the accumulation in them of the products of their own action (especially para-lactic acid); and secondly, from the exhaustion of the supply of oxygen. Hence rest is necessary, in order that the blood may neutralise and carry away the products of action, so that the muscle may recover its neutrality and its normal electrical currents, and may again acquire oxygen in sufficient quantity for the next contraction.

In the case of all muscles these intervals of action and of exhaustion take place, in part even of the period which is called exercise; but the rest is not sufficient entirely to restore it. In the case of the heart the rest between the contractions (about two thirds of the time) is sufficient to allow the muscle to perfectly recover itself.

The foregoing remarks on the effects of muscular exercise will have prepared us for the inference which statistics abundantly support, viz. that, other conditions being favorable, the healthiest occupation is that which consists in the practice (of course within reasonable limits) of manual labour in the open air.

The Rev. Professor Haughton, in his work entitled 'A New Theory of Manual Labour,' has drawn up a table (which we append) of the amount of force expended during various kinds of work. It represents the number of tons lifted one foot per diem:--

Professor Haughton has devised a formula by means of which a certain amount of walking exercise may be made to represent its equivalent in manual labour. He points out that walking on a level surface is equivalent to raising one twentieth part of the weight of the body through the distance walked.

When ascending any height, the whole weight of the body is, of course, raised through the ascent. The formula is--

(W + W_{l}) × D
---------------
20 × 2240

where W is the weight of the person; W_{l} the weight carried (if any); D the distance walked in feet; 20 the co-efficient of traction; and 2240 the number of pounds in a ton. The result is the number of tons raised one foot. To get the distance in feet 5280 must be multiplied by the number of miles walked.

Supposing a man to weigh 150 lbs. with his clothes, by the employment of the above formula we should arrive at the following results:--

+----------------------+------------+
| |Work done in|
| Kind of Exercise. |tons lifted |
| | 1 foot. |
+----------------------+------------+
| Walking 1 mile | 17·67 |
+----------------------+------------+
| Walking 2 miles | 35·34 |
+----------------------+------------+
| Walking 10 miles | 176·7 |
+----------------------+------------+
| Walking 20 miles | 353·4 |
+----------------------+------------+
| Walking 1 mile | |
| and carrying 60 lbs.| 24·75 |
+----------------------+------------+
| Walking 2 miles | |
| and carrying 60 lbs.| 49·5 |
+----------------------+------------+
| Walking 10 miles | |
| and carrying 60 lbs.| 247·5 |
+----------------------+------------+
| Walking 20 miles | |
| and carrying 60 lbs.| 495 |
+----------------------+------------+

From the above data something like a rough approximation may be formed of the daily amount of exercise requisite for a healthy male adult.

Since 500 tons lifted a foot is extremely hard work, the number of miles corresponding to this extreme amount of labour would, if persevered in, be objectionable.

Dr Parkes, regarding 300 tons lifted a foot as an average day's work for a healthy man, thinks that walking exercise equivalent to half that amount should be taken daily. This, or a 150 tons, represents a nine miles' walk. He, however, qualifies the suggestion by adding "that, as there is much exertion taken in the ordinary business of life, this amount may be in many cases reduced;" and concludes by saying, "It is not possible to lay down rules to meet all cases, but probably every man with the above facts before him could fix the amount necessary for himself with tolerable accuracy."

For muscular exercise to be safe and efficient, it must be taken under certain conditions and precautions. We have noticed the evil effects of immoderate bodily exertion on the heart. The lungs are no less seriously affected by an excessive indulgence in it, which shows itself in spitting of blood and in congestion of the pulmonary vessels. Congestion of the lungs brought on by overtaxed bodily strength very frequently causes the death of horses in the hunting field.

These facts, therefore, not only point to the importance of avoiding undue or extreme exertion,[293] but also to the necessity of ensuring the full and uncramped play of the respiratory organs during exercise, and the consequent removal of any impediment in the way of tight clothing that in any manner interferes with their freedom of exercise. Laboured respiration and sighing are indications of pulmonary congestion, and counsel temporary rest and abstention from exercise.

[Footnote 293: "There must be proper intervals of rest, or the store of oxygen, and of the material in the muscles which is to be metamorphosed during contraction, cannot take place."

--PARKES.]

The great augmentation in the excretion of carbon which leaves the lungs in the form of carbonic anhydride during exercise has been already referred to. As this carbon is derived from the food, it follows that in the intervals of exercise an increase of carbonaceous diet is necessary. For this purpose physiologists prefer the fatty to the amylaceous varieties of diet. It has been already stated why at the same time the nitrogenous food must be increased during periods of great exertion. There seems little doubt that water is the best drink that can be taken during moderate as well as great exercise.... It is best taken in small quantities and frequently. Spirits are decidedly prejudicial, and indispose to bodily exertion. They are hurtful because they lessen the exhalation of carbonic anhydride from the lungs. Trainers never allow them, and but very little wine or beer.

The thirst that not unfrequently accompanies exercise is due to the great escape of water from the skin which has been already alluded to. This liberation of moisture, being also accompanied, as already explained, by a large excretion of the chlorides and, perhaps, by other salts. Dr Parkes advises the use of an additional supply of chloride of sodium to the diet of those taking much exercise; he suggests that probably potassium chloride and phosphate might be added with advantage.

The evaporation from the skin has the effect of reducing the bodily temperature and rendering it equable. This temperature, however, falls very rapidly after exertion is over; and hence at this time it is always advisable to guard against the chance of a chill by covering the body over. Flannel forms the best protection. Keeping the skin clean by daily ablution greatly aids in the escape of fluid during exercise.

The large amount of carbonic anhydride given off by the lungs during bodily exercise explains the advantages of open air exercise, and why walking in the fresh air produces such excellent effects in some forms of dyspepsia. This increased exhalation of carbonic anhydride also points to the importance of thorough ventilation when indoor exercise is taken, particularly by large bodies of men or women, as in riding schools and on the treadmill. The mortality amongst miners, whose labour is performed in confined and ill-ventilated spaces is very great. According to Mr Simon, with the exception of those who work in the well-ventilated mines of Durham and Northumberland, the 300,000 miners in England break down prematurely from bronchitis and pneumonia, caused by the atmosphere in which they are compelled to work.

=EXPAN'SION.= All substances, solid, liquid, and gaseous, when chemical change does not take place, expand by heat, and contract by cold. In some of them this property occurs in a greater degree than in others, but is constant for the same substance under the same circumstances. The chemist avails himself of this property in the construction of his thermometer; the wheelwright, in fixing on the tire of his wheels; the engineer, in restoring to the perpendicular the leaning walls of buildings, &c.

This expansion by heat is of great importance in the manufactures, as allowance has to be made of it in every purpose where metals are employed.

The following is a list of the expansion of the chief metals, &c., when heated from 32° to 212° Fahr., or from 0° to 100° Cent.:--

_Substance._ _Expansion._
In bulk. In length.
Glass 1 in 384 1 in 1150
Platinum 1 in 377 1 in 1311
Steel 1 in 309 1 in 926
Iron 1 in 282 1 in 846
Gold 1 in 227 1 in 682
Copper 1 in 194 1 in 582
Brass 1 in 179 1 in 536
Silver 1 in 175 1 in 524
Tin 1 in 172 1 in 516
Lead 1 in 117 1 in 351
Zinc 1 in 113 1 in 340

Of the liquids, they expand as follows, when heated from 0° to 100° Cent., or from 32° to 212° Fahr.:--

Mercury 1 in 55 in bulk.
Water 1 in 21 in bulk.

Gases practically all expand alike; that is to say, for every degree Fahrenheit a gas expands 1/491 of its bulk at 32°, and for every degree Centigrade 1/273 of their volume at 0°C.

An example will show the importance of this. Suppose an iron bar, connecting two sides of a building, and of a length of about 85 feet. The increase in length by heat of this bar would make it 1 inch longer in summer than in winter; and it would, if no allowance be made, pull or thrust the walls to this extent each year.

=EXPEC'TORANTS.= _Syn._ EXPECTORANTIA, L. Medicines that promote the secretion of the trachial and bronchial mucus. According to Dr Good, true expectorants are "those medicines which rather promote the separation of the viscid phlegm with which the bronchiæ are loaded, than simply inviscate and dilute it; though these are also treated as expectorants by many writers." Ammoniacum, antimonials, assaf[oe]tida, the balsams of Peru and tolu, benzoic acid, benzoin; the fumes of vinegar, tar, and several of the volatile oils; garlic, ipecacuanha, the oleo-resins, squills, tartarised antimony, and the smoke of tobacco and stramonium, are among the principal substances commonly called expectorants. Tartarised antimony, squills, chlorine, and ammoniacal gases, have also been used (diluted) to provoke the coughing and favour the expulsion of foreign bodies from the air-passages; and also to favour the expectoration of mucus, pus, and membranous concretions, when the local irritation is not sufficiently great. (Schwilgue.) Expectorants are commonly employed in pulmonary complaints and affections of the air tubes, attended by a vitiated state of the mucus, or an imperfect performance of the natural functions of the secretory vessels. "Of all classes of the materia medica, none are more uncertain in their action than expectorants." (Pereira.) The act of ejecting matter from the chest is called EXPECTORATION.

=EXPER'IMENTS= are acts or operations intended to develop some unknown fact, principle, or effect; or to establish or demonstrate it, when discovered. Similar operations, performed merely for amusement, are also often, though incorrectly, called by this name. In rational experiments these two objects are combined. To experimental research is due the present high state of advancement and usefulness of the various sciences most intimately connected with our happiness and well-being. The danger of taking things for granted has been thus pleasantly and instructively pointed out by Archbishop Whately:--"It was objected to the system of Copernicus, when first brought forward, that if the earth turned on its axis, as he represented, a stone dropped from the summit of a tower would not fall at the foot of it, but at a great distance to the west; in the same manner as a stone dropped from the masthead of a ship in full sail does not fall at the foot of the mast, but towards the stern. To this it was answered, that a stone, being a part of the earth, obeys the same laws, and moves with it; whereas it is no part of the ship, of which, consequently, its motion is independent. The solution was admitted by some, but opposed by others; and the controversy went on with spirit; nor was it till one hundred years after the death of Copernicus that, the experiment being tried, it was ascertained that the stone, thus dropped from the head of the mast, _does_ fall at the foot of it."

=EXPORTATION.= (EXPORTATION ON DRAWBACK.) By law, a certain allowance, or drawback of duty, is payable on certain articles, when exported from any part of the United Kingdom, either as merchandise or ship stores. Thus:--

SUGAR, refined in the United Kingdom, from 4_s._ to 6_s._ per cwt., according to quality.

TOBACCO, manufactured in the United Kingdom, 3_s._ 3_d._ per lb. The full drawback is only allowed on normal tobacco, which contains 13 per cent. of moisture. If the moisture exceeds 13 per cent., a proportionate reduction is made in the drawback; if it is found less than 13 per cent., a proportionate increase is granted.

SNUFF is entitled to drawback at 3_s._ 3_d._ per lb., subject, however, to an increase if the moisture is less than 13 per cent., and the inorganic matter not over 18 per cent., and to a decrease if the moisture in organic matter exceeds these per-centages.

BEER. The amount of this drawback is proportional to the quantity of malt or sugar used in the brewing of the beer, and is nearly equivalent to the duty originally paid on such malt or sugar. It is computed according to the following scale:--For every barrel, or 36 gallons of beer, the original gravity of which was not less than 1040°, a drawback of 4_s._ 3_d._, and for every additional 5 degrees, from 1040° to 1125° inclusive, a further sum of 6_d._ per barrel.

SOLIDIFIED WORTS, made by a licensed brewer, from malt or sugar, or malt and sugar, a drawback of 2_s._ 10-5/100_d._ per 28 lbs.

MALT. Under certain restrictions, a drawback of the duty charged, after deducting 7-1/2 per cent. of the measured quantity.

SPIRITS, from 10_s._ to 10_s._ 3_d._ per proof gallon.

In all cases samples are taken by the Custom House officer, and forwarded to the Inland Revenue laboratory, where they are examined previous to the payment of the drawback.

=EXPRES'SION.= In the _useful arts_, the mechanical operation by which a fluid contained in the pores or cells of a solid is pressed out or expelled. Many of the fluid substances employed in pharmacy and chemistry are obtained by expression. Thus, the unctuous vegetable oils, as those of almonds, linseed, &c., are procured by submitting these substances to powerful pressure between iron plates, which are either made warm, or the bruised seeds are previously exposed in bags to the steam of boiling water. The juices of fresh vegetables are also obtained by expression. The substances are first bruised in a marble mortar, or, on the large scale, in a mill, and immediately submitted to the press, to prevent them passing into a state of fermentation, which would injure the quality of the product. Fruits which contain highly flavoured or fragrant seeds, or which have rinds containing essential oil, are generally deprived of them before being sent to the press. The subacid fruits are also allowed to lay together for some days before pressing them, as the quantity and quality of the product is thereby increased. The fluid matter absorbed by the ingredients employed in the preparation of tinctures, infusions, decoctions, extracts, &c., is generally obtained by powerful pressure. Expression is also frequently had recourse to for the purpose of obtaining solids in a state of purity, as in the expulsion of olein from stearin, water from bicarbonate of soda, &c. On the small scale, the common screw-press, or one of like construction, is usually employed; but the power thus obtained is insufficient to expel the whole of a fluid diffused through the pores of a solid. Hence has arisen the use of the hydraulic press, which is now almost alone employed on the large scale. In all these cases the substances are placed in bags made of haircloth, or coarse canvas, previously to their being submitted to pressure. For tinctures and like pharmaceuticals, a small screw-press (TINCTURE PRESS) made of 'galvanised' or tinned iron, and varying in capacity from 1 quart to several gallons, is employed.

=EXSICCA'TION.= See DESICCATION.

=EX'TRACT.= _Syn._ EXTRACTUM, L. Among _chemists_ this term is understood to apply to the residuum of the evaporation of aqueous decoctions or infusions of vegetable matter. In _medicine_ and _pharmacy_, it has a less definite signification, being applied to various preparations obtained by evaporating the expressed juices, or the decoctions, infusions, or tinctures of vegetable substances, until a mass, of a solid or semi-solid consistence is formed. Extracts vary in their nature and composition with the substances from which they are prepared, and the fluids employed as solvents. When water is employed as the menstruum, the products (AQUEOUS EXTRACTS, WATERY E.; EXTRACTA AQUOSA, E. SIMPLICIORA, L.) usually consist of gum, starch, sugar, albumen, extractive and saline and other matter, along with the peculiar principles on which the medicinal virtue of the vegetable depends. When spirit is employed as the solvent, the products (ALCOHOLIC EXTRACTS; EXTRACTA ALCOHOLICA, L.) contain most of the substances above enumerated, except the gum and starch, together with several other substances which are soluble in spirit, but which are either wholly or nearly insoluble in water; as resins, essential oils, and the proximate principles of vegetables. These preparations, with scarcely an exception, are considerably more powerful than the aqueous extracts of the same vegetables. In some cases proof spirit or under-proof spirit is employed, when the extracts (SPIRITUOUS EXTRACTS; EXTRACTA SPIRITUOSA, L.) generally possess properties between those of the above. In other cases, dilute acetic acid or acidulated water is employed as the menstruum, when the products (ACETIC EXTRACTS; EXTRACTA ACETICA, L.) possess much greater activity than when prepared with water; and would in many cases prove fatal, if exhibited in doses as large as those of the aqueous extracts. Still more active extracts are obtained by a combination of the last two menstrua. According to Ferrari, plants treated with rectified spirit of wine, mixed with 1/36th part of acetic acid, yields extracts of remarkable activity. On the Continent ether is sometimes used as the menstruum for the active principles of certain substances, as cantharides, cubebs, worm-seed, &c. (ETHEREAL EXTRACTS; EXTRACTA ETHEREA, L.) The term 'simple extract' is applied to an extract prepared from a single plant or vegetable substance, and the term 'compound extract' to one prepared from two or more of such substances. The FLUID EXTRACTS (EXTRACTA FLUIDA, L.) of modern pharmacy are those which are only evaporated to the consistence of a thin syrup, and then mixed with 1-10th to 1-8th of their volume of rectified spirit.

_Prep._ The preparation of medicinal extracts may be conveniently considered under two divisions, viz.--1. The production of a solution of the soluble portion of the substances operated on; and, 2. The reduction of this solution by evaporation to the consistence of an extract.

1. PREPARATION OF SOLUTIONS:--The preliminary operations in the manufacture of extracts are similar to those employed in the preparation of DECOCTIONS, INFUSIONS, and TINCTURES. The proper quantity of the ingredients being taken, the whole is well bruised or reduced to coarse powder, or otherwise divided by slicing with a knife, that every portion may be fully exposed to the solvent action of the fluid. In some few cases (as with gentian, &c.) the 'slicing,' or reduction to fragments, is often conveniently deferred until the action of the menstruum shall have so far softened the ingredients as to render them of easy division by the knife. Those substances (as sarsaparilla, chamomiles, &c.) whose medicinal principles reside in the cortical portion, of which are of easy solubility, are commonly subjected to the action of the menstruum without being subjected to any particular preparation.

In the preparation of AQUEOUS EXTRACTS, the ingredients are treated with water until all the soluble matter that it is desirable to obtain is dissolved out. There are several methods of effecting this object, depending upon the nature of the substances acted on. In some cases maceration in cold water is resorted to; in others percolation with that fluid in a 'displacement apparatus.' More generally, however, boiling water is poured on the substance, and is digested on it for some time, as in the preparation of infusions; or the substance is exhausted by boiling in water, as in the preparation of decoctions. After the ebullition or infusion has continued a sufficient time, the heat is removed, and the liquid portion drawn off. The ingredients are then pressed to extract the remaining liquid; or they are washed or 'sparged' with hot water, which expels it by displacement. According to the usual practice in the majority of cases, a second quantity of water is poured on after the first has been thoroughly drained off, and the effusion or decoction is repeated a second and even a third time, or until the ingredients are perfectly exhausted of their soluble portion. The liquor or liquors thus obtained being allowed to repose for 15 or 20 minutes, for the purpose of depositing the sand or other gritty and heavy matter that is mechanically mixed with them, are carefully decanted from the sediment, and, after being run through a fine hair-sieve, or flannel bag, are ready for concentration. In some instances, however, this method proves insufficient to render the liquid clear. In such cases, the solution may generally be rendered transparent by clarification with a little white of egg, removing the scum as it rises, straining the liquid through flannel, as before; or the liquid may be filtered through a bag made of fine 'Welsh flannel,' or of 'tweeled cotton cloth' (Canton flannel), both of which should be soaked in clean water for at least an hour before use. In the small way, filters of linen or paper are sometimes employed; but as all media sufficiently fine to render vegetable solutions transparent soon choke up, this filtration is objectionable, from the length of time it occupies. In some houses the aqueous infusion or decoction is allowed to repose for 24 hours, and then decanted and evaporated; but such a plan is objectionable, as, however smooth and glossy extracts so prepared may appear, their medicinal virtues are lessened by the lengthened exposure to the atmosphere.

When about one half of an aqueous solution has evaporated, it is often advantageous to repass it through a flannel or horsehair strainer, to remove the flocculi that generally form by the action of the heat and air. This is especially necessary with vegetable solutions prepared without boiling, and should be adopted whenever a smooth and slightly extract is desired.

Previous Next

Comments

Cooley's Cyclopædia of Practical Receipts and Collateral Information in the Arts, Manufactures, Professions, and Trades..., Sixth Edition, Volume IChapter II: Deposition of the Precious Metals (7)

0%31 min left in chapter