VOL. LXXVI,] PHILOSOPHICAL TRANSACTIONS. 77 



and brown. Tin in aqua regia gives a yellowish precipitate; gold a dilute yellow 

 and reddish brown; platina a flesh-coloured precipitate; and regulus of antimony 

 a yellowish red. Silver is precipitated black; and so is lead, both from the 

 nitrous and acetous acids. Sublimate corrosive appeared for an instant red; but 

 soon after its precipitate appeared partly black and partly white. The nitrous 

 solution of bismuth affords also a precipitate, partly black, partly white, and 

 partly reddish brown, and of a metallic appearance ; that of cobalt is also black 

 or deep brown. Arsenical solutions give yellow precipitates more or less red; 

 but those of zinc only a dirty white. 



Of the Constitution of Hepatic Air. — From an attentive consideration of the 

 above experiments, it is difficult to conclude that hepatic air consists of any 

 thing else than sulphur itself, kept in an aerial state by the matter of heat. 

 Every attempt to extract inflammable air from hepatic air, when drawn from 

 materials that previously contained nothing inflammable, namely, from alkaline 

 or calcareous hepars, proved abortive: on the contrary, when the materials could 

 previously supply inflammable air, as when martial carbonaceous and saccharine 

 compounds were employed, inflammable air, in ever so small a proportion, was 

 detected: nor could hepatic air be procured from the direct union of inflam- 

 mable air and sulphur, as we have seen. 



Of Phosphoric Hepatic Air. — As phosphorus, in respect to its constituent 

 partSp bears a strong resemblance to sulphur, Mr. K. was naturally led to 

 examine its phenomena when placed in the same circumstances : he therefore 

 gently heated about 10 or 12 grains of phosphorus, mixed with about half an 

 ounce of caustic fixed alkaline solution, in a very small phial, furnished with a 

 bent tube, and received the air over mercury. On the first application of heat 

 two small explosions took place, attended with a yellow flame and white smoke, 

 which penetrated through the mercury into the receiver ; these were followed by 

 an equable production of air. At last the phosphorus began to swell and froth, 

 and fearing the rupture of the phial, he stopped the tube to prevent the access 

 of atmospheric air, and removed the phial to a water tub, intending to throw it 

 in ; but in the mean while the phial burst with a loud explosion, by reason of an 

 obstruction in the tube, and a fierce flame immediately issued from it. However 

 he obtained about 8 cubic inches of air. 



This air was diminished very slightly, by agitation with an equal bulk of 

 water, and then became cloudy like white smoke, but soon after recovered its 

 transparency. On turning up the mouth of the tube to examine the water, the 

 unabsorbed air instantly took fire, and burned with a yellow flame without ex- 

 ploding, leaving a reddish deposit on the sides of the tube. Water impregnated 

 with phosphoric air, and over which this air had burned, slightly reddened tine- 



