washing the part freely with vinegar. The vertigo now increased, was accompanied by shiverings, extreme pallor, complete loss of sight, and entire prostration; even the power of speech was lost, but the intelligence was, throughout, preserved. The limbs were very cold, and as the sight returned the phenomena of double vision were manifested. These alarming symptoms were not altogether removed within a period of ten hours, but recovery ultimately took place.

DISEASE FROM SALTS OF SILVER.

If

When some of the salts of silver, the nitrate especially, are brought into contact with the skin, with moisture, they produce a dark stain, which, ordinarily, is only of temporary duration. the salt be taken internally in small quantities, and for a considerable time, the whole of the surface of the skin becomes dark in color. The discoloration or stain is fairly distributed over the surface, but is most marked in those parts of the body which are exposed to light, as the face and hands, in which parts I have known the stain to be as deep as the complexion of a mulatto. The discoloration gradually lessens in the course of years, and it may be somewhat reduced by medical art, but I have never known it pass away entirely.

DISEASE FROM ZINC.

Men engaged in bronze founding are subject to serious symptoms from inhaling the fumes of oxide of zinc. The fumes rise to the mouth of the workman and settle on the lips, causing sometimes a whitish efflorescence. After long exposure to these fumes choleraic attacks are induced, with shiverings and severe cramps in the muscles of the legs. Vomiting is induced, and the food taken undergoes a peculiar fermentation, causing water-brash. Zinc-plating and the manufacture of "corrugated zinc" are also attended with most pernicious results to health.

DISEASE FROM SODIUM CHLORIDE, COMMON SALT.

Seafaring men, and others who have lived for a long time on salted foods, are subjected to an induced disease called commonly "sea scurvy," but which is more correctly defined as "saline

purpura," inasmuch as it depends on the action of the salt which is taken with the food. The physical change induced consists of a modification in the state of the blood. The specific weight of the blood is unduly increased, the plastic constituents of the blood are held in too extreme a state of solubility, and the corpuscles are reduced in size and made irregular at their edges. The effect of these changes is to render the blood so fluid that it pours out of a wound or into the soft tissues with unnatural readiness. From such parts as the gums the blood exudes freely. It infiltrates into the skin, causing dark vascular blotches, purpuric spots, and, sometimes from a wounded surface, or even a weakened vascular surface, it flows so freely that danger of death from the loss of it becomes imminent. In addition to these changes there follow indirect modifications in other organs, owing to the readiness with which, in its unnatural saline condition, the blood attracts and condenses water. The nervous centres suffer in consequence, and extreme prostration is the result.

DISEASE FROM COPPER.

The salts of copper are sometimes productive of disease, the acetate being the most commonly offending substance. Food retained in copper vessels has become poisoned, and peas, beans, and other green vegetable products boiled in contact with copper, for the purpose of increasing or preserving the green color, have also been rendered poisonous. The symptoms are choleraic in character, and attended with severe irritation of the stomach and bowels. When the dose taken has been large, collapse and fatal exhaustion have supervened; or, the acute symptoms having subsided, long-continued irritation and even ulceration of the mucous tract of the intestinal canal have set in, followed by slow and imperfect recovery.

CHAPTER II.

ACQUIRED DISEASES FROM INORGANIC GASES AND VAPORS.

By a gas is meant a substance which is ordinarily known to us in the gaseous form of matter, like the air we breathe. A gas is incondensible into a liquid or solid under the ordinary atmospheric pressure, at common temperatures.

By a vapor is meant a more readily condensible aeriform fluid which has taken that form from a liquid or solid, under the influence of heat, and is diffused in the air. It is usual to speak of a vapor as being derived from the volatilization of some volatilizable body like water-vapor,-steam,-from heated water.

Sometimes gases or vapors, given off from various substances, are called fumes. The vapors given off from heated resin, from phosphorus which is being oxidized, from mineral acids, such as the nitric or hydrochloric, are commonly called fumes. I prefer to speak of them as gases or vapors.

Gases and vapors when inhaled pass, like the air, into the windpipe and lungs. Diffused with the air, they may reach the blood which has been sent from the right side of the heart to the lungs, and absorbed by it may enter the blood-stream and condense in it. They have, therefore, a general as well as a local action.

DISEASE FROM AMMONIA GAS.

In many industrial occupations ammonia gas is liberated in free quantities. In the process of felt hat-making shellac is dissolved in a weak solution of ammonia. The felt is then steeped in the solution, and the ammonia, volatilized by heat, charges the atmosphere with its vapor. In other occupations ammonia is liberated in the decomposition of ammoniacal salts. In a third class ammonia is given off from decomposing organic compounds. In all cases the workers are exposed to the ammoniacal gas.

Considerable difference of opinion exists on the question of the harm that is inflicted by the inhalation of ammonia. Some observers have arrived at the conclusion that the gas inflicts no injury, and I am of opinion that the injury is much less than might at first sight be supposed. When, however, the inhalation of ammonia is long continued, certain physical effects result which must be considered injurious. The blood is rendered unduly fluid, the corpuscles of the blood are changed in form and are made crenate, the oxidation of the blood is reduced, and the disease anæmia, which has already been described, is developed.

There are some occupations in which decomposing organic remains are present, and which yield to the air of the place where the labor is carried on an ammoniacal sulphur odor which is most offensive, and which even taints the clothes and person of the worker. Those who are engaged in the labor of making catgut strings and cords; those who are engaged in dressing skins into rugs, as fellmongers; and those who act as bone-sorters and boilers are specially subject to these odors. A woman who was engaged in the first of these occupations, and who came to a public dispensary, to which I was physician, for medical advice, was so offensive she could not be tolerated in the waiting room with the other out-door patients, and she had to come in after all the rest had gone. The odor from the fellmonger's yard and from the bone-boiler's premises is detectable even at long distances from the place. It would be assumed, at first thought, that the operatives, breathing for many hours every day such an atmosphere, must needs suffer from some marked disease. I am bound to say that the evidence in support of this suspicion is all but negative. I have been unable to discover any definite symptom of disease connected with these callings as the result of the labor. Neither can I find any statistical facts that illustrate an unusual mortality from such labor.

DISEASE FROM CARBON BISULPHIDE.

Of late years the very disagreeable volatile fluid, known originally as the alcohol of sulphur, then as sulphuret of carbon, and now as carbon bisulphide, has come into great use in various industrial pursuits. It is employed for taking grease out of wool; for extraction and purification of paraffine; for extraction of oil

from oil-cakes when pressure is of no further use; for draining the sawdust used in refining oil by filtration; for extracting grease from bones or kitchen refuse; and for extracting aromatic essences and perfumes from plants. But the most important use of carbon bisulphide is, perhaps, in the manufacture of caoutchouc articles, toy-balloons, and water-proofings. In making toy-balloons the bisulphide is used to dissolve the caoutchouc and bring it into such a state of softness as will allow it to yield to the blast of air from the bellows. In water-proofing, it is used for the varnishing with india-rubber. The peculiarity of the bisulphide of carbon is, that on its volatilization the substance dissolved in it is deposited, while it, itself, diffuses in vapor through the air.

The action of this vapor on the workmen was originally described by M. Delpech to the Academy of Medicine of Paris, on January 15th, 1856. The effects are peculiarly severe. They consist, first, of acute symptoms of anesthesia, with intoxication, which afterwards become chronic. The head is much affected at all times, and partial insanity is not infrequent. The taste is vitiated; the sight and hearing are troubled; the digestion is perverted so that the appetite is increased, even to gluttony, and there is persistent nausea. The breathing organs, the organs of the circulation, and all the secreting organs are deranged, and such enfeeblement results that the workers, so long as they continue at their work, are simply wretched.

No name can be found for this particular disease in the old classification of diseases. It is, in fact, a malady, sui generis, from which the victim of it suffers so long as he labors. The symptoms include derangement of mind as well as body. The disease approaches most nearly to the general paralysis of the insane, and we may classify it as cerebral paralysis.

Under an improved hygienic system, including better ventilation of the factories in which the bisulphide of carbon is used in the arts, the resultant dangers from its use, above described, have been greatly reduced during the last few years. They are not, however, as yet entirely removed.

DISEASE FROM CARBONIC OXIDE-GAS.

Carbonic oxide is the product of the imperfect combustion of carbon in oxygen. It is produced in large quantities whenever charcoal or coke is burned in common air, as is so often done in