1835.] Improvements in Science. Ill 



0-842. Boiling point 62° (143° F.) Very soluble in alcohol 

 and ether; acts with violence on deutoxide of mercury, 

 forming a compound of Hg + 2 Su + 4 Su + 4 C + 10 H. 

 So that the composition of mercaptan is4C + 10 H + 2Su. 

 The mercaptide of mercury melts at 86° C, resembles fused 

 chlorale of potash, it is decomposed at 175° C ; it is insoluble 

 in water. Mercaptide of gold consists of 2 Au + 4 C + 10 

 H + 2 Su, is an amorphous mass without colour, and is 

 not decomposed at 220°. Mercaptide of platinum resembles 

 that of mercury in composition. Mercaptides of potassium 

 and sodium are alkaline. 



Zeise conceives the state of the combination of the ele- 

 ments of mercaptan may be represented by (4 C + 10 

 H + S) + (2H +S.) Liebig makes it 4 C + 12H+2S. 

 Absorption of deutoxide of Azote by salts of Protoxide of 

 Iron. — Priestley first observed that the salts of protoxide of 

 iron absorb deutoxide of azote ; and Davy afterwards ascer- 

 tained that a cubic inch of a saturated solution of sulphated 

 protoxide of iron, absorbs 12 cubic inches of this gas. All 

 the soluble salts of protoxide of iron, without exception, 

 possess the property of absorbing a determinate proportion 

 of deutoxide of azote, which is proportional to the base. 

 To determine directly the quantity of gas absorbed, Liebig's 

 apparatus was employed by Pelligot, (Poggendorff's Ann. 

 xxxi. 24.) The apparatus was weighed, a determinate por- 

 tion of salt introduced, the weight noted, a little water 

 poured in, and the weight a third time observed, then it 

 was attached to a Woulf's bottle by means of a ribband of 

 caoutchouc, from which the dry gas was disengaged. By 

 means of this apparatus, with the necessary precautions, 

 he obtained the following results : — 



15*433 gr. (1 gramme) of anhydrous sulphated protoxide 

 of iron, absorb 4*07 cubic inches (66*7 cub. cent.) or 9* per 

 cent, of its weight. 15*433 gr. chloride of iron absorb 

 4*339 cubic inches (71*1 cub. cents) or 10*7 of its weight 

 per cent. 



The solutions which absorb deutoxide of azote are not 

 altered, for the salts remain in the state of a protoxide, and 

 can be restored to their former state by heat. Sometimes a 

 little peroxide of iron is formed, and a little azote is dis- 

 engaged, but these partial decompositions proceed from the 



