70 PHILOSOPHICAL TRANSACTIONS. [aNNO 1786. 



moil air to admit the combustion of part of the sulphur. 2dly, That the aerial, 

 or any other acid, combined with the alkali, must be expelled, before the alkali 

 will combine with the sulphur. Liver of sulphur exercises a strong solving 

 power on the earth of crucibles, and readily pierces t. rough them. 



The best liver of sulphur is made of equal parts of salt of tartar and sulphur; 

 but as about -f of the salt of tartar consists of air which escapes during the 

 operation, it seems that the proportion of sulphur predominates in the result- 

 ing compound; yet as some of the sulphur also sublimes and burns, it is not easy 

 to fix the exact proportion. lOOgrs. of the best, that is, the reddest liver of 

 sulphur, afford, with dilute marine acid, about 40 cubic inches of hepatic air, 

 in the temperature of 6o°: a quantity equivalent to about 13 grs. of sulphur. 



The marine acid is the best adapted to the production of hepatic air. If the 

 concentrated nitrous acid be used, it will afford nitrous air; but having diluted 

 some nitrous acid, whose specific gravity was 1.347, with 20 times its bulk of 

 water, he obtained, with the assistance of heat, as pure hepatic air as with any 

 other acid. The concentrated vitriolic acid, poured on liver of sulphur, afford but 

 little hepatic air without the assistance of heat, though it instantly decomposes the 

 liver of sulphur; and it is partly for this reason that the proportion of air is so 

 small; for it is during the gradual decomposition of sulphureous compounds that 

 hepatic air is produced. Distilled vinegar extricates this air in the temperature 

 of the atmosphere; but it is not pure, its peculiar smell being mixed with that 

 of vinegar. The acid of sugar also produced some quantity of this air in the 

 temperature of 59°. Having made some liver of sulphur, in which the propor- 

 tion of sulphur much exceeded that of the alkali, Mr. K. poured on part of it 

 some oil of vitriol, whose specific gravity was 1 .863 : by this means he obtained 

 hepatic air, so loaded with sulphur, that it deposited some in the tube through 

 which it was transmitted, and on the upper part of the glass receiver. This air 

 he transferred to another receiver; but though it was then perfectly clear and 

 transparent, and amounted to 6 cubic inches, yet the next morning the inside 

 of the glass was thickly lined with sulphur, and the air reduced to 1 cubic inch, 

 which was pure vitriolic air. He also procured this airYrom a mixture of 3 parts 

 filings of iron and one of sulphur, melted together, and treated with marine 

 acid. It is remarkable, that this sulphurated iron, dissolved in marine acid, 

 affords scarce any inflammable, but mostly hepatic air. A mixture of equal 

 parts filings of iron and sulphur, made into a paste with water, after heating 

 and becoming black, afforded hepatic air when an acid was poured on it; but 

 this hepatic air was mixed with inflammable air, which probably proceeded from 

 the uncombined iron. After a few days, this paste lost its power of producing 

 hepatic air. Mr. Bergman has remarked, that combinations of sulphur with 

 some other metals yield hepatic air. 



