cus in it, such as we observe now and then, after death, from Cynanche trachealis. The oesophagus exhibited no marks of disease; but the stomach had several inflamed spots upon it, and contained a matter of a brown appearance, and which emitted an offensive odour.

From the history of this dissection, and of many others in which much fewer marks appeared of violent disease in parts whose actions are essential to life, it is highly probable death is not induced in the ordinary manner in which malignant fevers produce it, but by a sudden or gradual suffocation. It is the temporary closure of this aperture which produces the dread of swallowing liquids: hence the reason why they are swallowed suddenly, and with intervals, in the manner that has been described; for, should the glottis be closed during the time of two swallows, in the highly inflamed state of the system which takes place in this disease, suffocation would be the immediate and certain consequence. The same difficulty and danger attend the swallowing saliva, and hence the symptom of spitting, which has been so often taken notice of in Hydrophobia. Solids are swallowed more easily than fluids, only because they descend by intervals, and because a less closure of the glottis is sufficient to favour their passage into the stomach. This remark is confirmed by the frequent occurrence of death in the very act of swallowing, and that too with the common symptoms of suffocation. To account for death from this cause, and in the manner that has been described, it will be necessary to recollect, that fresh air is more necessary to the action of the lungs in a fever than in health, and much more so in a fever of a malignant character, such as the Hydrophobia appears to be, than in fevers of a milder nature. An aversion from swallowing liquids is not peculiar to this disease. It occurs occasionally in the Yellow fever. It occurs likewise in the disease which has prevailed among the cats both in Europe and America, and probably in both instances from a dread of suffocation in consequence of the closure of the glottis, and sudden abstraction of fresh

air.

The seat of the disease, and the cause of death, being, I hope, thus ascertained, the means of preventing death come next under our consideration. Tonic remedies, in all their forms, have been administered to no purpose. The theory of the disease would lead us to expect a remedy for it in bloodletting. But this, though now and then used with success, is not its cure; owing, as we now see, to the mortal seat of the

discase being so far removed from the circulation as not to be affected by the loss of blood in the most liberal quantity. As well might we expect the inflammation and pain of a paronychia, or what is called a felon on the finger, to be removed by the same remedy. Purging and sweating, though occasionally successful, have failed in many instances; and even a salivation, when excited, (which is rarely the case) has not cured it. An artificial aperture into the windpipe alone bids fair to arrest its tendency to death, by removing the symptom which generally induces it, and thereby giving time for other remedies, which have hitherto been unsuccessful, to produce their usual salutary effects in similar diseases.* In removing faintness, in drawing off the water in ischuria, in composing convulsions, and in stopping hæmorrhages in malignant fever, we do not cure the disease, but we prevent death, and thereby gain time for the use of the remedies which are proper to cure it. Laryngotomy, according to Foureroy's advice, in diseases of the throat which obstruct respiration, should be preferred to tracheotomy, and the incision should be made in the triangular space between the thyroid and cricoid cartilages. Should this operation be adopted in order to save life, it will not offer near so much violence to humanity as imany other operations. We cut through a large mass of flesh into the bladder in extracting a stone. We cut into the cavity of the thorax in the operation for the empyema. We perforate the bones of the head in trepanning; and we cut through the uterus, in performing the Cæsarian operation, in order to save life. The operation of laryngotomy is much less painful and dangerous than any of them; and besides permitting the patient to breathe and to swallow, it is calculated to serve the inferior purpose of lessening the disease of the glottis by means of local depletion. After an aperture has been thus made through the larynx, the remedies should be such as are indicated by the state of the system, particularly by the state of the pulse. In hot climates it is, I believe, generally a disease of feeble re-action, and requires tonic remedies; but in the middle and northern States of America it is more commonly attended with so much activity and excitement of the bloodvessels, as to require copious blood-letting and other depleting remedies.

* The hoarse barking, or the total inability of mad dogs to bark, fayours still further the idea that the mortal seat of the disease is in the glots tis, and that the remedy which has been proposed is a rational one.

Should this new mode of attacking this furious disease be adopted, and become generally successful, the discovery will place the ingenious gentleman who suggested it in the first rank of the medical benefactors of mankind.

Before I conclude my letter, I have only to add a fact which may tend to increase confidence in a mode of preventing the disease which has been recommended by Dr. Haygarth, and used with success in several instances. The same dog which bit Mr. Todd's son, bit, at the same time, a cow, a pig, a dog, and a black servant of Mr. Todd's. The cow and pig died; the dog became mad, and was killed by his master. The black man, who was bitten on one of his fingers, exposed the wound for some time, immediately after he received it, to a stream of pump-water, and washed it likewise with soap and water. He happily escaped the disease, and is now in good health. That his wound was poisoned is highly probable, from its having been made eight hours after the last of the above animals was bitten, in which time there can be but little doubt of such a fresh secretion of saliva having taken place as would have produced the Hydrophobia, had it not been prevented by the above simple remedy. I am not, however, so much encouraged by its happy issue in this case as to advise it in preference to cutting out the wounded part. It should only be resorted to where the fears of a patient, or his distance from a surgeon, render it impossible to use the knife. Philadelphia, July 27, 1803.

ARTICLE II.

OBSERVATIONS on several METHODS of obtaining OXYGENOUS GAS in a very pure State. By JAMES WOODHOUSE, M. D. Professor of Chemistry in the University of Pennsylvania, &c.

A

CHEAP and easy method of obtaining oxygenous gas, perfectly pure, in large quantities, has long been a desideratum with chemists. The azotic air, with which this gas is generally contaminated, renders it improper to be used in many delicate operations. In decomposing hydrogen gas, carbonated hydrogen gas, and the oxyds of carbon, of the same quality, in the eudiometer of Volta, different results will happen, unless the oxygenous air be exactly of the same strength, or

unless it be completely freed of azotic air, which produces the variations in the experiments.

Dr. Priestley, who has had more experience in pneumatic philosophy than any other person, says, "to make dephlogisticated air perfectly pure is hardly possible;"* and the French and British philosophers recommend but one substance, the hyperoxygenated muriate of pot-ash, for this purpose.

This article is at present too dear in Europe to be much used by the chemist, and it cannot be procured in the United States.

Reflecting upon this subject, it occurred to me that an oxyd of mercury, prepared by boiling a solution of pot-ash upon turbith mineral, would afford the air in the state required.

Turbith mineral is made by boiling the sulphuric acid upon mercury, until a dry white salt is formed, upon which a large quantity of boiling water is poured. A part of the oxygen of the acid unites to the mercury, and converts it into an oxyd, which is dissolved by part of the acid forming sulphate of mercury. Another part of the oxygen of the acid seizes hold of part of its sulphur, and makes sulphureous gas, or volatile vitriolic acid, which escapes.

The hot water dissolves the sulphate of mercury, containing an excess of acid, and leaves a substance behind, of a yellow colour, which is called turbith mineral.

A considerable portion of sulphuric acid still adheres to this preparation, of which it may be freed by boiling it in a solution of pot-ash, but which cannot be separated by boiling it ever so long in water.

The pot-ash will unite to the sulphuric acid, and form sulphate of pot-ash, or vitriolated tartar; while the mercury will be left in the form of an oxyd of a brown colour. The sulphate of pot-ash being soluble in water, may be washed away from the oxyd of mercury.

The agents employed in manufacturing this article are sulphuric acid, or oxygen and sulphur, mercury, pot-ash, and water; neither of which, except the last, contains any azotic air, and this adheres to and is thrown away with the water. One ounce of an oxyd of mercury, prepared in this manner, submitted to a red heat in an iron tube, yielded forty cubic inches of oxygenous gas.

This air was examined by phosphorus, by the nitrous test, and by exploding it with hydrogen gas from sulphuric acid, diluted with water, and malleable iron.

* Medical Repository, vol. iii. p. 122.

A piece of phosphorus, the size of a duck-shot, was stuck upon the end of an iron wire, and introduced into one hundred parts of the gas, confined over water in an eudiometer. Upon approaching a lighted taper near the phosphorus, it immediately inflamed, an absorption of the water took place, and but two hundred parts of a measure of azotic air remained.

Four measures of nitrous air, from diluted nitric acid and copper, were added to one of this oxygen gas, in an eudiometer. The first gave an absorption of 120, the second 134, the third 150, and the fourth 70.

Two cubic inches of this oxygen air, and four of hydrogen gas, exploded by the electric spark, in the eudiometer of Volta, left one fourth of a cubic inch of air, which was principally azotic.

The materials and apparatus employed in making this oxyd of mercury are not very expensive, nor are the operations difficult or troublesome.

The acid may be boiled upon the mercury in an oil-flask, and the boiling water may be poured upon the dry sulphate of mercury in powder, in a queen's ware wash-hand bason. When the sulphate of mercury, containing an excess of acid, is washed away, the remaining sulphate of mercury, or turbith mineral, may be digested a few hours in a hot solution of pot-ash, which will free it from every particle of the sulphuric acid. The greatest part of the mercury may be saved when the air is obtained from the oxyd, for it will be found in a revived state in the iron tube.

If turbith mineral, which has not been digested with a solution of pot-ash, is exposed to a red heat in a close vessel, having a syphon in its mouth, it will afford oxygen gas, and a quantity of the sulphate of mercury of a white colour will sublime from it, adhere to the side of the vessel, and fill up the bore of the syphon; hence it is best to use the oxyd prepared from this salt by means of pot-ash.

A second method which was tried to procure oxygen gas in a pure state, was by exposing the leaves of vegetables to the influence of solar light, in pump-water, which generally contains a portion of carbonic acid, or in boiled and distilled water, impregnated with this air.

A small handful of the green leaves of any plant will yield six, eight, or ten cubic inches of oxygenous air, when exposed to the action of the sun in one hundred and forty cubic inches of the pump-water of this city; and, provided the air