On definite Proportions, 87 



with a metal ; whence it follows that sulphur is easily 

 freed by inelling from the moisture which adheres to it. 



With respect to Klaproth's analysis, it is not so accurate 

 as that of Bucholz. He treated 200 grains of pure sulphur 

 with nitric acid ; 4fiy grains remained unaltered, the ISlf, 

 which were oxygenized, afioided 10S2 of sulphate of 

 baryta, so that 100 parts of sulphur jjfave 15 less of the 

 sulphate than in Bucholz's experiment : and yet the ex- 

 periment was not repeated. At the same time it happens, 

 from the different estimates which these chemists have 

 formed of the composition of the sulphate of baryta, that 

 they agree in their determinations of the quantity of sul- 

 phur in the sulphuric acid. 



Richter's experiment (Richter v. 125) was performed in 

 a different manner. He converted 222 grains of flowers of 

 sulphur, by means of the smoking nitric acid, into sul- 

 phuric acid. The acid Hquor vvas saturated with carbonate 

 of lime, then dried and washed with alcohol and a little 

 nitric acid, to separate from it the nitrate and carbonate of 

 lime. The gypsum, when ianiled, weighed 947 grains. 

 Now, if 100 parts of this salt contain 58 of the acid, 947 

 must contain 549^; so that 222 grains of sulphur must 

 have taken up 3275 of oxygen, ^^^^ 100,147^: hence 100 

 parts of ihe acid must contain 40-44 of su'phur, which 

 agrees again very nearly v.ith my experiments already re- 

 lated. But if the proportion of acid in gypsum has been 

 taken a little too great, Richter's experiment approaches 

 still nearer to mine. Buchoiz obtained, in an analysis of 

 300 grains of gypsum, 63 grams of water of crystallization, 

 99 grains of lime, and 402 of ignited sulphate of baryta, 

 from which the presence of 136*7 gr. of sulphuric acid 

 may be inferred. Tliese quantities, added together, make 

 2G8'7 s;r. and the loss is only J -3, while, if we reckon 

 accordmii; to Bucholz's proportions, k becomes a little more 

 than 6 gr. Bucholz, finding this loss pretty constant in 

 several experiments, inferred from it that a part of the wa- 

 ter adhered to the gypsun., notwithstanding the ignition. 

 The component parts of gypsum, according to the propor- 

 tions here assigned, are 58 of acid, and 42 of lime; but 

 it is |trol)able, that in the analysis performed by Bucholz, 

 a loss ot lime also took place, by which the pn^porlion of 

 th'j acid to the base becomes loo great. Klaproth found 

 in Ignited gypsum 57'fi3 of acid, cind 42-37 of base. 



B. Sulphurom ^cid. 



To determine the coniposition of the sulphurous acid by 

 F 4 direct 



