On definite Proportions. 345 



afford 146'33 of sulphate of the protoxide, and according 

 to the experiments on the protoxide (B) 7"7 parts must re- 

 present the oxvaen oF the protoxide, there remain for the 

 sulphuric acid 38'63, which must contain 15-42 of sulphur, 

 that is, as much as conibinis wivh 100 parts of lead (A). 

 Consequently if 38-63 parts of sulphuric acid contain 

 15-42 of sulphur, this acid consists of 39'92 sulphur and 

 60-08 oxvgen. But since in my experiments the quantity 

 of sulphur in the sulphurei of lead is in all probability repre- 

 sented as somewhat too small, the sulphuric acid luay pos- 

 sibly contain a very little more sulphur than this proportion. 



I shall show, in the second part of this essay, that, to 

 judge from the calculations of the oxygenized carburetted 

 hydrogen gas, of the oxide of carbon, and of sulphuretted 

 hydrogen, a degree of oxidation corresponding to that of 

 the carbonic oxide must be possible for sulphur; and that 

 the sulphur must be to the oxygen very nearly in the pro- 

 portion of two to one; and I hope to make it probable that 

 this state of oxidation of sulphur is found in the sulphuretted 

 muriatic acid. In this case, 15'42 parts of sulphur must be 

 combined with 7*7 of oxygen. The same quantity of sul- 

 phur, with 2X7*7, that is, v.ith 15-4, of oxygen, will con- 

 sequently constitute the sulphurous acid, and with 3 x 7"7s 

 or 23*1, the sui|jhuric. . According to this view of the sub- 

 ject, the sulphuric acid nuist contain in 100 parts 40 03 

 of sulphur, and 59'97 of oxygen, the sulphurous, -iy9(j3 

 of sulphur, and 50-032 of oxvgen. If we calculate for the 

 sulphate of the protoxide of lead, according to these pro- 

 portions, we have 14-62 of this sulphate fur 10 of lead; 

 and this is precisely the result of the first of my former ex- 

 periments on this substance. 



From this view of the subject we may derive another " 

 mode of computing the composition of the sulphuric acid. 

 We see that the protoxide of lead, which saturates a given 

 quantity of sulphuric acid, contains exactly one-third as 

 much oxygen as the acid; and it must contain exactly h;iif 

 as much oxygen as the sulphurous acid by which it is sa- 

 turated, since the sulphites, in becoming sulphates by the 

 absorption of oxygen, do not alter their slate of neutralisa- 

 tion. Now, since 279 parts oi' the protoxide of leatl satu- 

 rate 100 of sulphuric acid, and these "^'TO parts contain 

 19"95 of oxygen ; consequently the sulphuric acid must 

 contain in 100 parts 59-85 of oxvgen, which differs only 

 by ToW fr'^*"' ihe former determination. Supposing the 

 analysis of the sulphate of t!ie protoxide of lead to be slightly 

 incorrect, and that for instance 100 parts of sulphuric acid 



saturate 



