and of removing the obftructions in the liver. I was induced therefore to try the folubility of gall ftones in mephitic water. But I have yet only a solitary experiment on the fubject to offer to you. A gall ftone, that had been extracted from a tumour in the region of the liver, was divided into two parts. One of thefe, which weighed fifty-one grains and a half, was immerfed four days in rain water, ftrongly impregnated with fixed air. The other weighed twenty grains and a quarter, and was macerated in fimple rain-water during the fame space of time. The firft fragment, when carefully dried, was become heavier by one grain, having gained fo much from the fixed air. In texture and appearance it remained unchanged. The fecond fragment had loft one eighth of a grain.

I mean not to draw any decifive inference from a fingle experiment. But it is probable that the Bath waters refolve concretions of the bile, not fo much by a chemical operation, as by accelerating the fecretions of the liver, ftimulating the organs of digeftion, and invigorating the whole animal fyftem. Nature indeed obferves a peculiar oeconomy in the circulation of the blood through the liver; and as the bile is one of her moft elaborate fluids, it must be difficult to introduce a foreign and unaffimilated fubftance into it. From analogy, however, we may conclude, that this is not impracticable. The milk and the faliva are frequently impregnated with adventitious matters; and these animal liquors, like the bile, are fecreted by organs of a particular structure, and for determinate and important purposes. A remedy which would pass unchanged into the fyftem of the liver, and me

dicate

dicate the bile, fo as to render it unapt to coagulate, or enable it to refolve the concretions already formed, would be a moft valuable acquifition *; and the obftacles to the attainment of it fhould rather be regarded as incitements to our industry, than apologies for fupineness and despair. Such, it must be acknowledged, they have proved; as appears from the variety of diffolvents which have been proposed and tried. Acids, alkalies, foap, ardent and dulcified fpirits, with fresh vegetable juices, have been recommended. Valifnerius found that a compofition of alcohol and oil of turpentine destroyed the texture and cohesion of gall ftones, more perfectly than any other menftruum † ; and Mr. William White of York has fully confirmed this obfervation, by a number of judicious experiments which he has communicated to me. Some time ago I thought favourably of this remedy, and endeavoured to promote the trial of it; but farther reflection has convinced me, that the continued ufe of it is more likely to prove injurious than beneficial. Spirituous liquors, of all forts, have a peculiarly unfavourable operation on the liver; and it would be abfurd to feek a specific medicine for the diseases of the bile, in what experience has fatally. fhewn to be a specific poifon to the organ which secretes it. Perhaps fixed air, under fome form or other, may hereafter be found to be the defideratum, which we have been fo long purfuing. At least, we may be allowed to attribute some share of the virtues which the Bath waters poffefs, to this ingredient in their compofition; and when they cannot be employed, to

Effays Medical and Experimental, vol. 2. p. 232.

recom

recommend the mephitic water, as an innocent and efficacious fubftitute.

I am, with fincere refpect and esteem,

Dear Sir,

Your most faithful and affectionate friend,

THO. PERCIVAL.

P. S. Since this letter was written, the young gentleman, whofe name I have before mentioned with respect, has at my defire taken large quantities of mephitic water daily, during the space of a fortnight. His urine became impregnated with fixed air, precipitated lime-water, and proved a powerful diffolvent of the calculi, which were immerfed in it.

Dr. Saunders, to whom I have communicated my observations on the folution of human calculi by mephitic water, has lately favoured me with a general account of his discoveries on this fubject. There is a perfect agreement in the refult of our experiments, and we propose to publish them together.

NUM

NUMBER III.

A Letter from Dr. DOBSON of Liverpool to Dr. PRIESTLEY, with Cafes of the Efficacy of FIXED AIR in putrid Disorders.

Dear Sir,

Liverpool, March 29, 1775.

My friend Dr. Percival has lately informed me, that you are about to publish a fupplement to your valuable work on fixed air.

:

The gentlemen of the faculty have not given that attention to the medical uses of fixed air, which I think it merits and a late medical writer, (vide Dr. Lettfom's Medical Memoirs of the Gener. Difpenf. P. 334.) doubts whether fixed air has any real efficacy even in diseases of a putrid class. I have tranfcribed therefore four cafes from a number of others, which are much at your service. If they are too late, or do not coincide with the intention of your present publication, please to return them, that they may be joined with fome other cafes and practical obfervations, which I fhall give to the public as foon as I have time to transcribe them.

That Dr. Priestley may long enjoy health, and the world reap the fruits of his philofophical labours, are the fincere wishes of his

Of the Efficacy of FIXED AIR in Fevers of the putrid Clafs.

Putrid fevers rarely acquire any great degree of malignancy in Liverpool, or its 'neighbourhood; and when they do appear, it is generally among the lower ranks of people. A fever of this kind crept into our public hospital in the spring of the year 1773, and a confiderable number were infected.

The following histories are transcribed from the notes, which were taken during my attendance on the respective patients.

Hiftory 1.

Mary Rainford, about 15 years of age, was admitted into the hofpital on account of convulfions ; fhe was fubject likewife every three or four weeks to vomit large quantities of blood, and was much enfeebled by these complaints at the time of her being feifed with the fever.

She first complained of pain and weight in the head, pain in the limbs and back, and a great degree of languor and dejection; fhe had frequent chills, alternating with flushes of heat, and got very little rest. The tartar emetic was twice given, and operated easily and powerfully by vomit; a blifter was applied between the thoulders; and a dofe of the following mixture was ordered to be taken every three hours.

R Sp.