VOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. 725 



the following experiment. A little pure sulphur was introduced into an inverted 

 tube, which had been previously filled with mercury, and the flame of a candle 

 was applied to the extremity of the tube. In a short time a permanently elastic 

 fluid was produced, which was found to have all the characters of hepatic air. 

 It is probable however, that some degree of moisture is necessary to the success 

 of this experiment, because the quantity of hepatic air which was thus obtained 

 was not very considerable. 



It has been already shown, that an oily matter was produced by the union 

 between fixed air, volatile alkali, and animal hepatic air. The following experi- 

 ment proves, that a substance, which has very much the appearance of oil, is 

 formed by the combination of sulphureous hepatic air with fixed air and volatile 

 alkali. A quantity of impure hepatic air was obtained by adding vitriolic acid to 

 common liver of sulphur. When this fluid was agitated with lime-water, it 

 produced a copious precipitation. It therefore contained a considerable propor- 

 tion of fixed air. One measure of it was now introduced into a slender gra- 

 duated tube, inverted over mercury, and was mixed with an equal bulk of alka- 

 line air. As soon as the airs came into contact with each other, a white cloud 

 was produced, the mercury began gradually to rise in the tube, and at the end 

 of 6 hours the air that remained occupied the space of only 1 measure and 4-. 

 The surface of the mercury within the tube first became black, and a part of it 

 afterwards acquired a red colour resembling cinnabar. In the course of the 

 experiment, a yellowish oleaginous substance was deposited on the interior sur- 

 face of the tube. This substance, in some parts of the surface, formed itself 

 into globules ; in others it was extended into ramifications, having the resem- 

 blance of trees in miniature, and it gradually assumed a deeper colour, till at 

 length it acquired a greenish cast. The substance, thus obtained, had a very 

 fetid odour : it appeared to have a near resemblance to an animal oil which had 

 become green by putrefaction. It was however soluble in water, and the odour 

 of the solution was increased by the vitriolic, and destroyed by the concentrated 

 nitrous and dephlogisticated marine acids. 



Mr. Cruikshank, who assisted in most of the foregoing experiments, and on 

 whose accuracy he could place the greatest reliance, examined, in Dr. C.'s ab- 

 sence, the red and black powders formed by the action of the hepatic air on the 

 surface of the mercury, and found them to be aethiops mineral, and cinnabar. 



Of the air extricated from animal substances by putrefaction. — In the begin- 

 ning of July, 1789, about 2 ounces of veal, slightly putrid, was introduced into 

 a large phial, filled with distilled water, and inverted over a quantity of the same 

 fluid. At the end of 3 days a few bubbles of air had appeared at the bottom of 

 the phial; the water had acquired a light brown colour, and emitted a fetid 

 smell. At the expiration of 7 days we could perceive that the quantity of air at 



