112 On the Daltonian Theory of [Ave. 



Number of Weight of an 



atoms. integrant particle. 



125. Sulphuret of antimony . .1 a -V 2 s 15-111 ^ 



126. Sulphuret of tellurium.. i / + 2 s 8*107 *» 



12/. Sulphuret of arsenic 1 , , . r± nn i* i 



' ', > 1 a + 1 s 8*000 ' 



or realgar J 



1 28. Orpiment 1 a + 2 s 1 0-000 



129. Sulphuret of cobalt ....1 c + 1 5? 9-326? f 



130. Sulphuret of manganese 1 m + 1 s 9*130 l 



2-009 is almost exactly the weight of an atom of sulphur. Ac- 

 cording to Lagerhjelm, 100 bismuth combine with 22*52 sul- 

 phur. Now 100 : 22-52 :: 8-994 : 2-030. This comes also 

 very near the weight of an atom of sulphur. 



p According to Berzelius, sulphuret of antimony is composed 

 of 100 antimony + 37 sulphur. (Larbok i Kemien, ii. 162.) 

 Now 100 : 37 :: ll'lll : 4-111. According to Mr. John Davy, 

 42-5 antimony combine with 14*86 sulphur. Now 42-5 : 14-S6 

 :: 11-111 : 3-S85. The mean of the two numbers 4-111 and 

 3*885 is 3*998, which is almost exactly the weight of 2 atoms of 

 sulphur. 



** According to Davy, tellurium by fusion combines with 

 nearly its own weight of sulphur. Now as an atom of tellurium 

 weighs 4-107, it * s clear that the sulphuret must contain 2 atoms 

 of sulphur. 



r 1 do not know in what manner Thenard ascertained the 

 composition of the sulphuret of arsenic; but he informs us that 

 realgar is a compound of 3 arsenic + 1 sulphur. Now 3:1:: 

 6 : 2. Hence it must be a compound of 1 atom arsenic and 1 

 atom sulphur. Orpiment, he says, is composed of 4 arsenic -f- 

 3 sulphur. Now 4 : 3 :: 6 : 4*5. This does not differ very 

 much from the weight of 2 atoms of sulphur. Hence the pro- 

 portions given in the table. (See Ann. de Chim. lix. 284.) 

 Laugier has lately endeavoured to prove that there is only one 

 sulphuret of arsenic, composed of 42 sulphur and 58 arsenic. 

 (Ann. de Chim. Ixxxv. 26.) If he be correct, it is a compound 

 of 1 atom arsenic with 2 atoms sulphur. 



s We know but imperfectly the composition of sulphuret of 

 cobalt. Proust says that 100 parts of cobalt absorb 40 of sul- 

 phur. (Ann. de Chim. Ix. 272.) But he puts little confidence 

 in the result of his own experiment. Now 100 : 40 :: 7'326 : 

 2-9304. As 2-9304 approaches nearest to I atom of sulphur, I 

 have supposed the sulphuret a compound of 1 atom cobalt and 1 

 atom sulphur; but the estimate is entitled to little confidence. 



1 We have no good data for determining the composition of 

 sulphuret of manganese. Vaucjuelin made a combination of 



