Chapter XLVII: Part IX: Inorganic Poisons (5)

There are “mass-poisonings” by acetate of lead on record, which afford considerable insight into the varying action of this salt on different individuals. A case (_e.g._) occurred at Stourbridge in 1840,[841] in which no less than 500 people were poisoned by thirty pounds of lead acetate being accidentally mixed with eighty sacks of flour at a miller’s. The symptoms commenced after a few days; constriction of the throat, cramping and twisting pains round the umbilicus, rigidity of the abdominal muscles, dragging pains at the loins, cramps and paralysis of the lower extremities. There was obstinate constipation; the urine was scanty and of a deep red colour, and the secretions were generally arrested; the pulse was slow and feeble; the countenance depressed, often livid; and the gums showed the usual blue line. The temperature of the skin was low. In only a few cases was there sickness, and in these it soon ceased. It is curious that not one of the 500 cases proved fatal, although some of the victims were extremely ill, and their condition alarming. It was specially observed that, after apparent convalescence, the symptoms, without any obvious cause, suddenly returned, and this even in a more aggravated form. Remittance of this kind is of medico-legal import; it might, for example, be wrongly inferred that a fresh dose had been taken. In the 500 cases there were no inflammatory symptoms; complete recovery took some time. On examining the bread the poison was found so unequally distributed that no idea could be formed as to the actual amount taken.

[841] Recorded by Mr. Bancks, _Lancet_, May 5, 1849, p. 478.

There is also recorded[842] an outbreak of lead-poisoning among 150 men of the 7th Infantry at Tione, in the Southern Tyrol. One case proved fatal, forty-five required treatment in hospital. The symptoms were pallor, a blue line in the gums, metallic taste in the mouth, a peculiar odour of the breath, a loaded tongue with a bluish tint, obstinate constipation with loss of appetite whilst all complained, in addition, of dragging of the limbs and of the muscles of the chest, and difficulty of breathing. In the severer cases there were tetanic spasms, muscular tremors, and anæsthesia of the fingers and toes. The pulse and temperature were normal, save in a few cases in which there were fever and sweats at night. _In none was there colic_, but the constipation was obstinate. In two of the worst cases there was strangury. Acute cases occur occasionally from poisoning by _the carbonate of lead_. Dr. Snow recorded an instance (in 1844) of a child who had eaten a piece as big as a marble, ground up with oil. For three days the child suffered from pain in the abdomen and vomiting, and died ninety hours after taking the poison. In another case, in which a young man took from 19 to 20 grms. of lead carbonate in mistake for chalk as a remedy for heartburn, the symptoms of vomiting, pain in the stomach, &c., commenced after a few hours; but, under treatment with magnesic sulphate, he recovered.

[842] Königschmied, _Centralbl. Allg. für Gesundheitspflege_, 2 Jahrg., Heft 1.

=The chromate of lead= is still more poisonous (see Art. “Chromium”).

§ 782. =Chronic Poisoning by Lead.=--Chronic poisoning by lead--often caused by strange and unsuspected channels, more frequently an incident, nay, almost a necessity, of certain trades, and occasionally induced by a cunning criminal for the purpose of simulating natural disease--is of great toxicological and hygienic importance. In the white-lead trade it is, as might be expected, most frequently witnessed; but also in all occupations which involve the daily use of lead in almost any shape. The chief signs of chronic poisoning are those of general ill-health; the digestion is disturbed, the appetite lessened, the bowels obstinately confined, the skin assumes a peculiar yellowish hue, and sometimes the sufferer is jaundiced. The gums show a black line from two to three lines in breadth, which microscopical examination and chemical tests alike show to be composed of sulphide of lead; occasionally the teeth turn black.[843] The pulse is slow, and all secretions are diminished. Pregnant women have a tendency to abort. There are also special symptoms, one of the most prominent of which is often lead colic.

[843] The black line soon develops; Masazza has seen it in a dog, exposed to the influence of lead, in so short a period as three days (_Riforma med._, 1889, Nos. 248-257, 1).

In 142 cases of lead-poisoning, treated between 1852 and 1862 at the Jacob’s Hospital, Leipzig, forty-four patients (or about 31 per cent.) suffered from colic. Arthralgia--that is, pains in the joints--is also very common; it seldom occurs alone, but in combination with other symptoms. Thus, in seventy-five cases of lead-arthralgia treated at Jacob’s Hospital, in only seven were pain in the joints without other complications, fifty-six being accompanied by colic, five by paralysis, and seven by other affections of the nervous system. The total percentage of cases of lead-poisoning, in which arthralgia occurs, varies from 32 to 57 per cent.

Paralysis, in some form or other, Tanqueril[844] found in 5 to 8 per cent. of the cases, and noticed that it occurred as early as the third day after working in lead. The muscles affected are usually those of the upper extremity, then the legs, and still more rarely the muscles of the trunk. It is only exceptionally that the paralysis extends over an entire limb; it more usually affects a muscular group, or even a single muscle. Its common seat is the extensors of the hand and fingers; hence the expression “dropped-wrist,” for the hands droop, and occasionally the triceps and the deltoid are affected. The paralysis is usually symmetrical on both sides. Although the extensors are affected most, the flexors nearly always participate, and a careful investigation will show that they are weakened. If the paralysis continues, there is a wasting and degeneration of the muscle, but this is seen in paralysis from any cause. The muscular affection may cause deformities in the hands, shoulders, &c. Anæsthesia of portions of the skin is generally present in a greater or less degree. A complete analgesia affecting the whole body has been noticed to such an extent that there was absolute insensibility to burns or punctures; but it is usually confined to the right half of the body, and is especially intense in the right hand and wrist.

[844] Tanqueril des Planches, _Traité des Maladies de Plomb_, Paris, 1839. Tanqueril’s monograph is a classical work full of information.

§ 783. The older writers recognised the toxic effect of lead on the nervous system. Thus Dioscorides speaks of delirium produced by lead, Aretaeus of epilepsy, and Paul of Ægina refers to it as a factor of epilepsy and convulsions. But in 1830, Tanqueril first definitely described the production of a mental disease, which he called “_lead encephalopathy_.” This he divided into four forms--(1) a delirious form; (2) a comatose; (3) a convulsive; and (4) a combined form, comprising the delirious, convulsive, and comatose. Dr. Henry Rayner,[845] and a few other English alienists, have directed their attention to this question; and, according to Dr. Rayner’s researches, the number of male patients admitted into Hanwell Asylum, engaged in trades such as plumbing, painting, and the like, is larger in proportion to the number admitted from other trades than it should be, compared with the proportion of the various trades in the county of Middlesex, as ascertained from the census. Putting aside coarse lead-poisoning, which may occasionally produce acute mania, the insanity produced by prolonged minute lead intoxications possesses some peculiar features. It develops slowly, and in nearly all cases there are illusions of the senses, of hearing, taste, or smell, and especially of sight. Thus, in one of Dr. Rayner’s cases the patient saw round him “wind-bags blown out to look like men,” apparitions which made remarks to him, and generally worried him. Besides this form, there is also another which closely resembles general paralysis, and, in the absence of the history, might be mistaken for it.

[845] See an important paper, “Insanity from Lead-Poisoning,” by Drs. H. Rayner, Robertson, Savage, and Atkins, _Journ. of Mental Science_, vol. xxvi. p. 222; also a paper by Dr. Barton, _Allgemeine Zeitschrift für Psychiatrie_, Bd. xxxvij. H. 4, p. 9.

§ 784. The degenerative influence on the organ of sight is shown in six of Dr. Robertson’s patients, whose insanity was ascribed to lead--four of the six were either totally or partially blind.

The amaurosis has been known to come on suddenly, and after a very brief exposure to lead, _e.g._, a man, thirty-four years of age, after working for three days in a white-lead factory, was seized with intense ciliary neuralgia, had pains in his limbs and symptoms of lead-poisoning, and the right eye became amaurotic.[846] This form of impairment or loss of vision is different from the _Retinitis albuminurica_,[847] which may also be produced as a secondary effect of the poison; the kidneys in such cases being profoundly affected. The kind of diseased kidney produced by lead is the granular contracted kidney.

[846] Samelsohn, _Monatsbl. f. Augenheilk._, vol. xi. p. 246, 1873. See also a case of lead amaurosis, described by Mr. W. Holder, _Pharm. Journ._, Oct. 14, 1876.

[847] Ran, _Arch. f. Ophthal._, vol. i. (2), p. 205, 1858, and Schmidt’s _Jahrbuch_, Bd. cxxxiii. p. 116; Bd. cxliii. p. 67.

Eulenberg speaks of the sexual functions being weakened, leading to more or less impotence.

Lewy,[848] in 1186 patients suffering from lead-poisoning, has found caries or necrosis in twenty-two cases, or about 1·8 per cent.; fifteen were carious affections of the upper jaw, four of the fore-arm, two of the thigh, and one of the rib and sternum. Epilepsy and epileptiform convulsions occur in a few cases; it is very possible that the epilepsy may be a result of the uræmic poisoning induced by diseased kidneys.

[848] _Die Berufskrank. d. Bleiarbeiter_, Wien, 1873, S. 61.

Five cases of fatal poisoning occurred between 1884-6 among the employés of a certain white-lead factory in the east of London. The cases presented the following common characters. They were all adult women, aged from 18 to 33, and they had worked at the factory for short periods, from three to twelve months. They all exhibited mild symptoms of plumbism, such as a blue line round the gums, and more or less ill-defined indisposition; paralyses were absent. They were all in their usual state of health within a few hours or days preceding death. Death was unexpected, mostly sudden. In four cases it was preceded by epileptic fits and coma; but in the fifth case no convulsions were noted, although they may have occurred in the night.

The author[849] had an opportunity of investigating by chemical means the distribution of lead in the fourth and fifth cases in the liver, kidney, and brain.

[849] “The Distribution of Lead in the Brains of two Lead Factory Operatives,” _Journ. of Mental Science_, Jan. 1888.

In the fourth case, from 402 grms. of liver 24·26 mgrms. of lead sulphate were separated. The right kidney (weighing 81 grms.) yielded 5·42 mgrms. of lead sulphate. The brain was dehydrated with alcohol, and then treated with ether, hot alcohol, and chloroform until an albuminoid residue remained; lead was extracted from each of these portions, viz., the alcohol used for dehydration, the ethereal and chloroform extracts, and the albuminoid residue, as follows:--

Mgrms. of Lead
Sulphate.
Soluble in cold alcohol, 1·11
Soluble in ether and chloroform and hot alcohol, 25·47
Albuminoid residue, 7·76
34·34

In the fifth case, the brain was examined more in detail, and the lead present estimated in the following solutions and substances:--

1. Alcohol used for dehydration. This may be called “the watery extract,” for, after the brain has remained in strong alcohol for some weeks, the result is that the alcohol contains much water and substances extracted with water.

2. White matter--(_a_) from cerebrum; (_b_) from cerebellum.

3. Kephalin--(_a_) from cerebrum; (_b_) from cerebellum.

4. Ether extract, kephalin-free--(_a_) from cerebrum; (_b_) from cerebellum.

5. Substances soluble in cold alcohol--(_a_) from cerebrum; (_b_) from cerebellum.

6. The albuminoid residue--(_a_) from cerebrum; (_b_) from cerebellum.

The general results were as follows:--

Cerebrum, Cerebellum,
460·8 grms. 156·2 grms.
Mgrms. of PbSO₄. Mgrms. of PbSO₄.

White matter freed from kephalin
by ether, 0·0 5·0
Kephalin, 1·5 6·0
Ether extract, kephalin-free, 0·0 0·0
Substances soluble in cold alcohol, 0·0 0·0
Albuminoid residue, 40·0 6·0
---- ----
41·5 17·0

The aqueous extract contained 1·5 mgrm. of lead sulphate. In neither of the cases did the pathologist ascertain the total weight of the brain, but, presuming that the weight was an average weight, and that the lead in the remainder of the brain was similarly distributed, the amount of lead calculated as sulphate would amount to 117 mgrms. From these results it appears to the author probable that lead forms a substitution compound with some of the organic brain matters. This view would explain the absence of changes apparent to the eye found in so many of the fatal cases of lead encephalopathy.

§ 785. Lead taken for a long time causes the blood to be impregnated with uric acid. In 136 cases of undoubted gout, 18 per cent. of the patients were found to follow lead occupations, and presented signs of lead impregnation.[850]

[850] “On Lead Impregnation in Relation to Gout,” by Dyce Duckworth, M.D., _St. Barth. Hosp. Reports_, vol. xvii., 1881.

Ellenberger and Hofmeister[851] found that, with chronic poisoning of sheep with lead, excretion of hippuric acid ceased, and the output of uric acid was diminished. This may be explained by the formation of glycocol being arrested.

[851] _Arch. f. wiss. u. pract. Thierheilk._, Bd. x., 1884.

§ 786. There are some facts on record which would seem to countenance the belief that disease, primarily caused by an inorganic body like lead, may be transmitted. M. Paul (_e.g._) has related the history of the offspring (thirty-two in number) of seven men, who were suffering from lead-poisoning--eleven were prematurely born and one still-born; of the remaining twenty, eight died in the first year, four in the second, and five in the third year, so that of the whole thirty-two, only three survived three years.

The influence of the poison on pregnant women is, indeed, very deleterious. M. Paul noted that in four women who were habitually exposed to the influence of lead, and had fifteen pregnancies, ten terminated by abortion, two by premature confinement, three went the full term, but one of the three children was born dead, a second only lived twenty-four hours; so that, out of the whole fifteen, one only lived fully. In another observation of M. Paul’s, five women had two natural confinements before being exposed to lead. After exposure, the history of the thirty-six pregnancies of these women is as follows:--there were twenty-six abortions (from two to five months), one premature confinement, two infants born dead, and five born alive, four of whom died in the first year.

Chronic poisoning may be nearly always accounted for by the inhaling of lead dust, or by the actual swallowing of some form of lead; but, if we are to accept the fact narrated by the late Dr. Taylor, viz., that he himself had an attack of lead colic from sitting in a room for a few hours daily, in which there was a large canvas covered with white lead and drying oil, and one or two other similar cases,[852] we must allow that there is some subtle volatile organic compound of lead evolved. In the present state of our knowledge, it seems more reasonable to account for such cases by the suggestion that lead has entered the system by an unsuspected channel.

[852] The gate-keeper of a graveyard at Bordeaux continually used the remnants of crosses, covered with lead paint, to replenish his fire; the chimney smoked; gradually paralysis of the extensors of the right wrist developed itself, and he suffered from colic and other signs of lead-poisoning.--Marmisse, _Gaz. des Hôpit._, No. 25, 1866.

In 1882, a very interesting case occurred at Keighley, in which a mechanic, aged 42, died from the supposed effects of lead-poisoning, induced from drinking the town water, which was proved by Mr. Allen to contain about ⅗ of a grain of lead per gallon. For six months he had been out of health, and a week before his death he suffered from colic, vomiting, constipation, and a blue line round the gums, and occasional epileptiform seizures. After death the kidneys were found granular, and the heart somewhat enlarged. The viscera were submitted to Mr. Allen for analysis; no lead was found in the heart or brain, a slight, non-estimable trace in the kidneys, and about a grain was separated from the liver and spleen. Dr. Tidy, who was called in as an expert, gave a very guarded opinion, rather against the theory of direct lead-poisoning; and the verdict returned by the jury was to the effect that the deceased died from granular kidney, accelerated by lead-poisoning. Murder by the administration of doses of sugar of lead is rare, but such a case has occurred.

At the Central Criminal Court, in December 1882, Louisa Jane Taylor was indicted for poisoning Mary Ann Tregillis at Plumstead, and convicted. From the evidence it appeared that the prisoner, who was thirty-six years of age, came to reside with Mr. and Mrs. Tregillis, an aged couple of eighty-five and eighty-one years respectively. The prisoner was proved to have purchased at different times an ounce and half an ounce of sugar of lead, and to have added a white powder to the medicine of Mrs. Tregillis. The illness of the latter extended from about August 23 to October 23--a period of two months. It is difficult to say when the first dose could have been given, but it was probably some time between August 13 and 23, while the administration, without doubt, ceased on or before October 6, for on that date different nursing arrangements were made. The symptoms observed were nausea, vomiting, pain in the pit of the stomach, burning in the throat, very dark teeth, a blue line round the gums, and slight jaundice. There was great muscular weakness, with trembling of the hands, and a week before death there was paralysis of the right side.

Lead was discovered in most of the viscera, which were in great part normal, but the kidneys were wasted, and the mucous membrane blackened. The actual quantity of lead recovered by analysis was small, viz., 16·2 mgrms. (¼ grain) from the liver; from 8 ounces of brain, 3·2 mgrms. (1/20 grain); from half of the stomach, 16·2 mgrms. (¼ grain); and from the spleen, the kidneys, and the lungs, small quantities. It is, therefore, probable that, if the whole body had been operated upon, the yield would have been more than ·15 grm. (a little over 2 grains); but then, it must be remembered that the deceased lived, at least, seventeen days after the last dose.

§ 787. =Post-mortem Appearances.=--In acute cases of poisoning by the acetate, there may sometimes be found a slight inflammatory appearance of the mucous membrane of the stomach and intestines. Orfila considered that streaks of white points adherent to the mucous membrane were pathognomonic; but there have been several cases in which only negative or doubtful signs of inflammatory or other action have presented themselves. A general contraction of the intestines has often been noticed, and is of considerable significance when present; so also is a grey-black mucous membrane caused by deposited lead sulphide. Loen found in dogs and guinea-pigs, poisoned by lead, local inflammation areas in the lungs, liver, and kidneys; but in no case fatty degeneration of the epithelial cells of the liver, kidneys, or intestines. As a rule, no unabsorbed poison will be found in the stomach; the case related by Christison, in which a person died on the third day after taking at a single dose some large quantity of acetate of lead; and at the autopsy a fluid was obtained from the stomach, which had a sweet metallic taste, on evaporation smelt of acetic acid, and from which metallic lead was obtained--is so very extraordinary in every respect, that its entire accuracy is to be questioned. In death from chronic lead-poisoning, there is but little that can be called diagnostic; a granular condition of the kidneys, and all the pathological changes dependent on such a condition, are most frequently seen. If the patient has suffered from colic, a constriction of portions of the intestine has been noticed; also, in cases in which there has been long-standing paralysis of groups of muscles, these muscles are wasted, and possibly degenerated. In instances, again, in which lead has induced gout, the pathological changes dependent upon gout will be prominent. The blue line around the gums, and sometimes a coloration by sulphide of lead of portions of the intestines, may help a proper interpretation of the appearances seen after death; but all who have given any attention to the subject will agree that, simply from pathological evidence, it is impossible to diagnose chronic lead-poisoning.

§ 788. =Physiological Action of Lead.=--The action of lead is still obscure, but it is considered to have an effect mainly on the nervous centres. The paralysed muscles respond to the direct current, but not to the induced, leading to the suspicion that the intramuscular terminations of the nerves are paralysed, but that the muscular substance itself is unattacked. On the other hand, the restriction of the action to groups of muscles supports the theory of central action.

The lead colic is due to a true spasmodic constriction of the bowel, the exciting cause of which lies in the walls of the bowel itself; the relief given by pressure is explained by the pressure causing an anæmia of the intestinal walls, and thus lessening their sensibility. The slowing of the pulse produced by small doses is explained as due to a stimulation of the inhibitory nerves; and, lastly, many nervous phenomena, such as epilepsy, &c., are in part due to imperfect elimination of the urinary excreta, causing similar conditions to those observed in uræmia.

§ 789. =Elimination of Lead.=--When a large dose of acetate or carbonate is taken, part is transformed into more or less insoluble compounds--some organic, others inorganic; so that a great portion is not absorbed into the body at all, but passes into the intestines, where, meeting with hydric sulphide, part is changed into sulphide, colouring the alvine evacuations black. Some of the lead which is absorbed is excreted by the kidneys, but the search often yields only traces. Thudichum[853] states that in fourteen cases of lead-poisoning, in two only was obtained a weighable quantity from a day’s urine; in the remaining twelve lead was detected, but only by the brownish colour produced in an acid solution of the ash by hydric sulphide.

[853] _Pathology of the Urine_, p. 550.

The elimination of lead by the kidneys is favoured by certain medicines, such, for example, as potassic iodide. Annuschat found in dogs poisoned by lead from 3·8 to 4·1 mgrms. in 100 c.c. of urine; but, after doses of potassic iodide, the content of lead rose to 6·9 and even to 14 mgrms. Lead appears to be eliminated by the skin, being taken up by the epithelial cells, and minute, insoluble particles coming away with these cells. If a person who has taken small doses of lead for a time be placed in a sulphur water-bath, or have his skin moistened with a 5 per cent. solution of sodium sulphide, the upper layer of the epidermis is coloured dark; but the perspiration excited by pilocarpin or other agency contains no lead.

§ 790. =Fatal Dose=--(_a._) =Sugar of Lead.=--It may almost be said that it is impossible to destroy human life with any single dose likely to be taken or administered. In three cases an ounce (28·3 grms.) has been taken without fatal result. Although it must be allowed that repeated moderate doses, extending over some time, are more dangerous to health and life than a single large dose, yet there seems to be in some individuals a great tolerance of lead. Christison has given ·18 grm. in divided doses daily for a long time without any bad effect, save the production of a slight colic. Swieten has also given daily 3·9 grms. (60 grains) in ten days without observing toxic effects. That, in other cases, less than a grain per gallon of some lead compound dissolved in drinking-water, or in some way introduced into the economy, causes serious illness, is most inexplicable.

(_b._) =The Basic Acetate= in solution is more poisonous apparently than the acetate--60 c.c. (1½ drms.) have caused serious symptoms.

(_c._) =The Carbonate of Lead.=--Doses of anything like 28 grms. (an ounce) would probably be very dangerous to an adult; the only case of death on record is that of a child who took some unknown quantity, probably, from the description of the size of the lump, about 10 grms. (2½ drms.).

§ 791. =Antidotes and Treatment.=--Soluble sulphates (especially magnesic sulphate) have been given largely in both acute and chronic cases; in the acute, it stands to reason that it is well to ensure the presence of plenty of sulphates in the stomach and intestines, in order to form the sparingly soluble lead sulphate, should any residue remain; but to expect this double decomposition to go on in the blood and tissues is not based upon sound observation. The chronic lead-poisoning is best treated by removal from the source of mischief, the administration of large quantities of distilled water, and medicinal doses of potassic iodide.

§ 792. =Localisation of Lead.=--In a dog, which was killed by chronic lead-poisoning, Heubel found in the bones 0·18 to 0·27 per 1000 of lead; in the kidneys, 0·17 to 0·20; liver, 0·10 to 0·33; spinal cord, 0·06 to 0·11; brain, 0·04 to 0·05; muscles, 0·02 to 0·04; in the intestines traces, 0·01 to 0·02; in the spleen, the blood, and the bile, he also only found traces. Ellenberger and Hofmeister found in the kidneys of the sheep, 0·44 to 0·47; liver, 0·36 to 0·65; pancreas, 0·54; salivary glands, 0·42; bile, 0·11 to 0·40; bones, 0·32; fæces, 0·22; spleen, 0·14; central nervous system, 0·07 to 0·18; blood, 0·05 to 0·12; flesh, 0·05 to 0·08; urine, 0·06 to 0·08; and in the unstriped muscles and the lungs, 0·03 per 1000 of lead.

Without going so far as to say that lead is a natural constituent of the body, it is certain that it may be frequently met with in persons who have been apparently perfectly healthy, and quite free from all symptoms of lead-poisoning. Legrip found in the liver and spleen of a healthy person, 5·4 mgrms. of lead oxide in every kilogram; Oidtmann, in the liver of a man fifty-six years of age, 1 mgrm. of lead oxide per kilogram, and in the spleen 3 mgrms. per kilogram. Hence, the analyst, in searching for poison, must be very careful in his conclusions. Grave and serious errors may also arise from complications; suppose, _e.g._, that a deceased person previous to death had partaken of game, and inadvertently swallowed a shot--if the analyst had not carefully searched the contents of the stomach for _solid_ bodies, but merely treated them at once with acid solvents, he would naturally get very decided lead reactions, and would possibly conclude, and give evidence to the effect, that a poisonous soluble salt of lead had been administered shortly before death.

§ 793. =Detection and Estimation of Lead.=--A great number of fluids (such as beer, wines, vinegar, water, &c.), if they contain anything like the amount of one-tenth of a milligramme in 100 c.c., will give a very marked dark colour with SH₂. It is, however, usually safest in the first place to concentrate the liquid, to add an acid, and deposit the lead on platinum, in the way to be shortly described. Nearly all the lead from oils and fatty matter may be dissolved out by shaking up the fat with dilute nitric acid; if necessary, the fat should previously be melted.

If (in the usual course of routine research) a hydrochloric acid solution is obtained from the treatment or destruction of organic substances by that agent, and lead sulphide (mixed possibly with other sulphides) is filtered off, any arsenical sulphide may first be extracted from the filter by ammonia, and any antimonious sulphide by sodic sulphide; then the sulphide may be extracted by warm hydrochloric acid, which will leave undissolved such sulphides as those of copper and mercury. On diluting the liquid, and filtration at a boiling temperature, crystals of lead chloride will be deposited on cooling.

If, however, organic matters are _specially_ searched for lead, hydrochloric acid is not the best solvent, but nitric should always be preferred; and, if there is reason to think that the lead exists in the form of sulphate, then the proper solvent is either the acetate or the tartrate of ammonia; but, in either case, the solution should contain an excess of ammonia. It must, however, be remembered that organic matters retain lead with great tenacity, and that in all cases where it can with any convenience be effected, the substances should be not only carbonised, but burnt to an ash; for Boucher has shown[854] that carbon retains lead, and that the lead in carbon resists to a considerable extent the action of solvents.

[854] _Ann. d’Hygiène_, t. xli.

In the case of sulphate of lead, which may be always produced in an ash from organic substances by previous treatment with sufficient sulphuric acid, a very excellent method of identification is to convert it into sugar of lead. To do this, it is merely necessary to boil it with carbonate of ammonia, which changes it into carbonate of lead; treatment with acetic acid will now give the acetate; the solution may (if the lead is in very small quantity) be concentrated in a watch-glass, a drop evaporated to dryness on a circle of thin microscopic glass, and the crystals examined by the microscope; the same film next exposed to the fumes of SH₂, which will blacken it; and lastly, the solution (which should be sweet) tasted. A crystalline substance, possessing a sweet taste, and blackening when exposed to SH₂, can, under the circumstances, be no other substance than acetate of lead.

If the analyst does not care for this method, there is room for choice. Lead in solution can be converted into sulphide; in this case it is, however, absolutely necessary that there should be no great excess of acid, since as little as 2·5 per cent. of free hydrochloric acid will prevent all the lead going down. On obtaining the sulphide, the latter, as already described, can be converted into chloride by hydrochloric acid, and the crystalline chloride is extremely characteristic.

From the solution of the chloride the metal may be obtained in a solid state by inserting a piece of zinc in the solution contained in a crucible; the lead will be deposited gradually, and can be then collected, washed, and finally fused into a little globule on charcoal. A lead bead flattens easily when hit with a hammer, and makes a mark on paper. Solutions of the chloride also give a heavy precipitate of lead sulphate, when treated with a solution of sodic sulphate.

When lead is in very minute quantity, an electrolytic method is generally preferable; the lead is precipitated on platinum by using exactly the same apparatus as in Bloxam’s test, described at p. 566; the liquid to be tested being placed in the inner cell, the lead film may now be identified, dissolved in nitric acid, and estimated by a colorimetric process. For the estimation of the minute fractions of a grain by a colour method, it is merely necessary to have a very dilute solution of acetate of lead, to add a known volume of SH₂ water to the liquid to be tested in a Nessler cylinder, noting the colour, and add to another a known quantity of the standard lead solution and the same quantity of SH₂ as was added to the first.

The process has an advantage which is great, viz., that it either detects copper, or proves its absence at the same time; and there are few cases in which the analyst does not look for copper as well as for lead. Lead, if in sufficient quantity, may be most conveniently estimated as oxide, sulphate, or chloride; the chief properties of these substances have been already described.

§ 794. =The Detection of Lead in Tartaric Acid, in Lemonade, and Aërated Waters.=--To detect lead in tartaric acid a convenient method is to burn it to an ash, digest in a little strong sulphuric acid, and then add either sodic chloride or a drop of HCl; lead, if present, is precipitated as chloride, giving a pearly opalescence. Lemonades often contain minute quantities of iron and copper as well as lead. Neither copper nor iron are precipitated by ammonium sulphide in presence of potassic cyanide. On the other hand, the sulphide of lead is not soluble in the alkaline cyanides. Hence a liquid which, on the addition of potassium cyanide and then ammonium sulphide, becomes dark coloured, or from which a precipitate separates, contains lead.[855]

[855] F. L. Teed, _Analyst_, xvii. 142-143.

2. COPPER.

§ 795. =Copper=, Cu = 63·5; specific gravity, from 8·921 to 8·952; fusing-point, 1091° (1996° F.). Copper in analysis occurs either as a film or coating on such metals as platinum, iron, &c., or in a state of fine division; or, finally, as a bead. In thin films, copper has a yellowish or a yellowish-red colour; it dissolves readily in nitric, slowly in hydrochloric acid. If air be excluded, hydrochloric acid fails to dissolve copper, and the same remark applies to ammonia; but, if there be free access of air, ammonia also acts as a slow solvent. Metallic copper in a fine state of division can be fused at a white heat to a bright bluish-green globule, which, on cooling, is covered with black oxide.

§ 796. =Cupric Oxide= (CuO = 79·5; specific gravity, 6·5, composition in 100 parts, Cu 79·85, O 20·15) is a brownish-black powder, which remains in the absence of reducing gases unaltered at a red heat. It is nearly insoluble in water, but soluble in ClH, NO₃H, &c.; it is hygroscopic, and, as every one who has made a combustion knows, is readily reduced by ignition with charcoal in the presence of reducing gases.

§ 797. =Cupric Sulphide=, CuS = 95·5, produced in the wet way, is a brownish powder so insoluble in water that, according to Fresenius, 950,000 parts of water are required to dissolve one part. It is not quite insoluble in ClH, and dissolves readily in nitric acid with separation of sulphur. By ignition in a stream of H it may be converted into the subsulphide of copper. It must always be washed by SH₂ water.

§ 798. =Solubility of Copper in Water and Various Fluids.=--The solubility of copper in water and saline solutions has been very carefully studied by Carnelley.[856] Distilled water exerts some solvent action, the amount varying, as might be expected, according to the time of exposure, the amount of surface exposed, the quantity of water acting upon the copper, &c. It would appear that, under favourable circumstances, 100 c.c. of distilled water may dissolve ·3 mgrm. of copper (·2 grain per gallon).

[856] _Journ. Chem. Soc._, 1876, vol. ii. p. 4.

With regard to salts, those of ammonium exert a solvent action on copper more decided than that of any others known. With the others, however, the nature of the base exerts little influence, the action of the salt depending chiefly on the nature of its acid radical. Thus, beginning with the least effective, the following is the order of dissolving strength:--Nitrates, sulphates, carbonates, and chlorides. It will then at once be evident that a water, contaminated by sewage, and therefore containing plenty of ammonia and chlorides, might exert a very considerable solvent action on copper.

Almost all the oils and fats, as well as syrups, dissolve small quantities of copper; hence its frequent presence in articles of food cooked or prepared in copper vessels. In the very elaborate and careful experiments of Mr. W. Thompson,[857] the only oils which took up no copper, when digested on copper foil, were English neats’-foot oil, tallow oil, one sample of olive oil, palm-nut oil, common tallow oil, and white oil, which was protected from the air by a thick coating of oxidised oil on its surface.

[857] “Action of Fatty Oils on Metallic Copper,” _Chem. News_, vol. xxxiv. pp. 176, 200, 313.

The formation of copper compounds with the fatty acids takes place so readily that Jeannel[858] has proposed the green colouring of fats by copper as a test for the presence of copper; and Bottger[859] recommends a copper holding brandy to be shaken up with olive oil to free it from copper.

[858] _L’Union pharmac._, xvii. 81.

[859] _Arch. de Pharm._, 1853, cxxvi. 67.

Lehmann has made some useful researches on the amount of copper taken up by fats under different conditions. 100 c.c. of strongly rancid fat dissolved in fourteen days 8·7 mgrms. of copper; but when heated to 160° for one hour, and then allowed to stand, a similar amount was found. Some rancid butter was rubbed into a brass bowl of 90 c.c. capacity, and then allowed to stand for twenty-four hours; the butter became of a blue-green colour. Into this dish, thus partially attacked by fatty acids, 50 c.c. of rancid butter was poured in a melted condition, and allowed to stand for twenty-four hours. The amount taken up was found to be equal to 10 mgrms. of copper for every 100 c.c. of fluid butter.

Hilger found a fatty soup, which had stood twelve hours in a clean copper vessel, to contain 0·163 per cent. copper. According to Tschirch, the easiest fatty salt to form is the oleate, hydrated copper oxide dissolving in oleic acid with great ease, and even copper oxide dissolving to some extent; the palmitate and the stearate are not so readily produced; hence the amount of copper dissolved is greater in the case of olive oil and butter (both rich in oleic acids) than in the case of the firmer animal fats. Acid solutions, such as clarets, acetic acid, vinegars, and so forth, as might be expected, dissolve more or less copper. The amount likely to be dissolved in practice has been investigated by Lehmann. He steeped 600 square metres of copper sheeting or brass sheeting in vessels holding 2 litres of acid claret; the sheets were in some of the experiments wholly immersed, in others partly so. More copper was dissolved by the wine when the copper was partly immersed than when it was wholly immersed; and more copper was dissolved from brass sheeting than from pure copper sheeting. With a sheet of copper, partly immersed, claret may contain as much as 56 mgrms. per litre. Lehmann also investigated the amount of copper, as acetate, which could be dissolved in wine before the taste betrayed its presence: with 50 mgrms. per litre no copper taste; with 100 mgrms. there was a weak after taste; with 150 mgrms. it was scarcely drinkable, and there was a strong after taste; with 200 mgrms. per litre it was quite undrinkable, and the colour was changed to bluish-green. Vinegar, acting under the most favourable circumstances on sheet brass or copper, dissolved, in seven days, 195 mgrms. of copper per litre from the copper sheet, 195 from the brass sheet.

Lehmann discusses the amount of copper which may be taken at a meal under the circumstance that everything eaten or drank has been artificially coppered, but none “coppered” to the extent by which the presence of the metal could be betrayed by the taste; and the following is, he thinks, possible:--

300 c.c. of soup boiled in a copper vessel, 20 mgrms. Cu.
1 litre of wine which has been standing in a
copper vessel, 50 „
50 c.c. vinegar which has been kept in a copper
vessel, 10 „
50 grms. of fat which has been used for frying in a
copper vessel, 5 „
200 grms. of strongly coppered peas, 50 „
500 grms. of strongly coppered bread, 60 „

The total only amounts to 195 mgrms. of copper, which only slightly exceeds a high medicinal dose. The metal is tasted more easily in liquids, such as wine, than in bread; bread may be coppered so that at a meal a person might eat 200 mgrms. of a copper compound without tasting it.

It is pretty well accepted that cooking in clean bright copper vessels will not contaminate any ordinary food sufficiently to be injurious to health.

§ 799. =Copper in the Vegetable and Animal Kingdom and in Foods.=--Copper is widely distributed in the vegetable kingdom, and is a constant constituent of the chief foods we consume; the following quantities, for example, have been separated from the chief cereals:--

Wheat, 5·2 to 10·8 mgrms. per kilo.
Rye, 5 mgrms. „
Oats, 8·5 „ „
Barley, 11·8 „ „
Rice, 1·6 „ „
Bread, 1·5 to 4·4 mgrms. „

It has also been found in vermicelli (2-10 mgrms. per kilo.), groats (1·6-3 mgrms. per kilo.), potatoes (1·8 mgrm. per kilo.), beans (2-11 mgrms. per kilo.). In similar small quantities it has also been found in carrots, chicory, spinach, hazel-nuts, blackberries, peaches, pears, figs, plums, tamarinds, black pepper, and many other fruits and spices. The most common food which has a high copper content is cocoa, which contains from 12 mgrms. to 29 mgrms. per kilo., the highest amount of copper being in the outer husk; copper has also been found in many supplies of drinking water, in aërated waters, in brandies, wines, and many drugs.

It has been calculated that the ordinary daily food of an average man contains the following:--

Copper.
900 grms. bread, 0·45 mgrm.
260 grms. meat, 0·25 „
200 grms. fruit and vegetables, 0·25 „
----
0·95 mgrm.

That is to say, that, neglecting altogether foods artificially contaminated with copper, each of us eats daily about 1 mgrm. of copper (0·015 grain).

In the animal kingdom it is a constant and natural constituent of the blood of the cephalopods, crustacea, and gasteropods, and is nearly always present in the liver and kidneys of domestic animals, as well as in men. Dr. Dupré[860] found ·035 to ·029 grain (1·8 to 2 mgrms.) in human livers, or about 1 part in 500,000. Bergeron and L. L’Hôte’s researches on fourteen bodies, specially examined for copper, fully substantiate those of Dr. Dupré; in twelve the copper was found in quantities of from ·7 to 1·5 mgrm.; in the remaining two the amount of copper was very minute, and was not estimated.[861] Copper is also found normally in the kidneys, and Dupré [862] detected in human kidneys about 1 in 100,000 parts; it is also found in the bile, and in minute traces in the blood.[863]

[860] _Analyst_, No. 13, 1877.

[861] _Compt. Rendus_, vol. lxxx. p. 268.

[862] _Op. cit._

[863] Hoppe-Seyler, _Handbuch der physiologisch. Analyse_, p. 415.

In the kidneys and livers of the ruminants copper may always be found, a sheep’s liver containing about 1 part in 20,000.[864] Church found copper in the feathers of the wings of the turaco; melopsitt in the feathers of a parroquet (_Melopsittacus undulatus_).[865] In these cases the copper enters into the composition of the colouring matter to which the name of “turacin” has been given. Turacin contains 7 per cent. of copper, and gives to analysis numbers which agree with the formula of C₈₂H₈₁Cu₂N₉O₃₂.

[864] Dupré, _op. cit._

[865] _Chem. News_, xxviij. 212.

Copper has been discovered in aërated waters, its presence being due to the use of copper cylinders, the tin lining of which had been rendered defective by corrosion.[866]

[866] “On the Presence of Lead and Copper in Aërated Waters,” by Dr. James Milne, _Chem. News_, xxxi. p. 77.

Accidents may also occur from the use of copper boilers. Mr. W. Thompson found in one case[867] no less than 3·575 grains in a gallon (51 mgrms. per litre) in water drawn from a kitchen boiler.

[867] _Chem. News_, xxxi. No. 801.

At Roubaix, in France, sulphide of copper had been deposited on the roof, as a consequence of the use of copper flues; the sulphide was changed into sulphate by the action of the air, and washed by the rain into the water-tank.[868]

[868] Author’s _Dictionary of Hygiène_, p. 167.

That preserved vegetables are made of a bright and attractive green colour by impregnation with copper, from the deliberate use of copper vessels for this purpose, is a fact long known. Green peas especially have been coloured in this way, and a number of convictions for this offence have taken place in England.

§ 800. =The “Coppering” of Vegetables.=--The fact that green vegetables, such as peas, beans, cucumbers, and so forth, preserve their green colour, if boiled in copper vessels, has long been known. In this “coppering” the French have been more active than the English traders; the French operate in two different ways. One method is, to dip from 60 to 70 litres of the green vegetables in 100 litres of 0·3 to 0·7 per cent. of copper sulphate, to leave them there for from five to fifteen minutes, then to remove them, wash and sterilise in an autoclave. A second method is to put the vegetables into a copper vessel, the wall of which is connected with the negative pole of an electric current, the positive pole dips in a solution of salt in the same vessel, the current is allowed to pass for three minutes, and the vegetables are afterwards sterilised. Fruits are simply allowed to stand with water in copper vessels, the natural acidity of the juice dissolving sufficient copper.

The amount of copper taken up in this way is appreciable, but yet not so much as might be expected; the prosecutions for selling “coppered” peas in England have been based upon quantities varying from 1 to 3 grains per lb.; the highest published amount of copper found in peas artificially coloured is 0·27 per kilo., or 18·9 grains per lb.

The reason why vegetables preserve their green colour longer when treated with a copper salt has been proved by Tschirch[869] to be owing to the formation of a phyllocyanate of copper.

[869] _Das Kupfer_, Stuttgart, 1893.

Phyllocyanic acid is a derivative of chlorophyll, and allied to it in composition; the formula of C₂₄H₂₈N₂O₄ has been ascribed to it. Under the action of acids generally, mineral or organic, chlorophyll splits up into this acid and other compounds. Copper phyllocyanate, (C₂₄H₂₇N₂O₄)₂Cu, contains 8·55 per cent. of copper; it forms black lamellæ, dissolving easily in strong alcohol and chloroform, but insoluble in water; it is a little soluble in ether, insoluble in petroleum ether, and dissolved neither by dilute acetic acid, nor by dilute nor concentrated hydrochloric acid. The compound dissolves in caustic alkali on warming. In alcohol it forms a beautiful non-fluorescent solution. A solution of 1 : 100,000 is still coloured strongly green.

This solution, in a stratum of 25 mm. thick, gives four absorption bands when submitted to spectroscopic observation, and Tschirch has worked out a process of estimation of the amount of copper phyllocyanate based upon the disappearance of these bands on dilution.

Green substances, so carefully treated that they only contain phyllocyanate of copper, would yield but small quantities of copper, and probably they would not be injurious to health; but the coppering is usually more extensive, and copper leguminate and other compounds are formed; for the vegetables, when exhausted by alcohol, give a residue which, successively exhausted by water, by soda-lye, and lastly by hydrochloric acid, parts with copper into the three solvents mentioned.

It might be argued that, from the insoluble character of the phyllocyanate of copper, and especially seeing that it does not dissolve in strong hydrochloric acid, that it would be perfectly innocuous; but Tschirch has proved that, whether the tartrate of copper (dissolving easily in water), or copper oxide (not dissolving at all in water, but soluble in hydrochloric acid), or phyllocyanate of copper (insoluble both in water and in hydrochloric acid) be used, the physiological effect is the same.

Copper may be found in spirits, owing to the use of copper condensers, a remark which applies also to the essential oils, such as _oleum cajepute_, _menthæ_, &c.[870] In France, it has been added fraudulently to absinthe, to improve its colour.[871] Green sweetmeats, green toys, green papers, have all been found to contain definite compounds of copper to a dangerous extent.

[870] According to Eulenberg (_Gewerbe Hygiene_, p. 716), _Oleum cajepute_, _Menth. pip._, _Melissæ_, _Tanaceti_, &c., are almost always contaminated with copper.

[871] Tardieu, _Étude Méd. Lég. sur l’Empoisonnement_.

§ 801. =Preparations of Copper used in Medicine and the Arts.=

(1) =Medicinal Preparations=:--

=Sulphate of Copper=, =Cupri Sulphas=, CuSO₄5H₂O.--This well-known salt is soluble in water at ordinary temperature, 3 parts of water dissolving 1 of the sulphate; but boiling water dissolves double its weight; 1 part of copper sulphate dissolves in 2½ of glycerin; it reddens litmus, and is slightly efflorescent; its solution responds to all the usual tests for copper and sulphuric acid. A watery solution of the salt to which twice its volume of a solution of chlorine has been added, gives, when treated with ammonia in excess, a clear sapphire-blue solution, leaving nothing undissolved, and thus showing the absence of iron. Besides iron, sulphate of copper has been found to contain zincic sulphate.

=Nitrate of Copper=, Cu(NO₃)₂3H₂O, is officinal; it is very soluble.

=Cuprum Aluminatum.=--A preparation, called cuprum aluminatum (_Pierre divine_), is in use in France and Germany, chiefly as an external wash. It is composed of 16 parts cupric sulphate, 16 potassic nitrate, 16 alum, fused in a crucible, a little camphor being afterwards added.

Regular and irregular medical practitioners, veterinary surgeons, farriers, and grooms, all use sulphate of copper (bluestone) as an application to wounds. Copper as an _internal_ remedy is not in favour either with quacks or vendors of patent medicines. The writer has not yet found any patent pill or liquid containing it.

(2) =Copper in the Arts.=--Copper is used very extensively in the arts; it enters into the composition of a number of alloys, is one of the chief constituents of the common bronzing powders, is contained in many of the lilac and purple fires of the pyrotechnist, and in a great variety of pigments. The last-mentioned, being of special importance, will be briefly described:--

=Pigments=:--

=Schweinfurt and Scheele’s Green=[872] are respectively the aceto-arsenite and the arsenite of copper (see article “Arsenic”).

[872] The synonyms for Schweinfurt green are extremely numerous:--Mitic green, Viennic green, imperial green, emerald green, are the principal terms in actual use.

=Brighton Green= is a mixture of impure acetate of copper and chalk.

=Brunswick Green=, originally a crude chloride of copper, is now generally a mixture of carbonate of copper and chalk or alumina.

=Mountain Green=, or =Mineral Green=, is the native green carbonate of copper, either with or without a little orpiment.

=Neuwieder Green= is either the same as mountain green, or Schweinfurt green mixed with gypsum or sulphate of baryta.

=Green Verditer= is a mixture of oxide and carbonate of copper with chalk.

=Verdigris= is an acetate of copper, or a mixture of acetates. Its formula is usually represented as (C₂H₃O₂)CuO. It is much used in the arts, and to some extent as an external application in medicine. Its most frequent impurities or adulterations are chalk and sulphate of copper.

§ 802. =Dose--Medicinal Dose of Copper.=--Since sulphate of copper is practically the only salt administered internally, the dose is generally expressed as so many grains of sulphate. This salt is given in quantities of from ·016 to ·129 grm. (¼ to 2 grains) as an astringent or tonic; as an emetic, from ·324 to ·648 grm. (5 to 10 grains).

The sulphate of copper is given to horses and cattle in such large doses as from 30 up to 120 grains (1·9 to 7·7 grms.); to sheep, from 1·3 to 2·6 grms. (20 to 40 grains); rabbits, ·0648 to ·1296 grm. (1 to 2 grains).

§ 803. =Effects of Soluble Copper Salts on Animals.=--Harnack has made some experiments on animals with an alkaline tartrate of copper, which has no local action, nor does it precipitate albumin. ½ to ¾ mgrm. of copper oxide in this form, administered subcutaneously, was fatal to frogs, ·05 grm. to rabbits, ·4 grm. to dogs. The direct excitability of the voluntary muscles was gradually extinguished, and death took place from heart paralysis. Vomiting was only noticed when the poison was administered by the stomach.[873] The temperature of animals poisoned by copper, sinks, according to the researches of F. A. Falck, many degrees. These observations are in agreement with the effects of copper salts on man, and with the experiments of Orfila, Blake, C. Ph. Falck, and others.

[873] On the other hand, Brunton and West have observed vomiting produced in animals after injection of copper peptone into the jugular vein.--_Barth. Hosp. Rep._, 1877, xii.