294 On the Daltonian Theory of [Oct. 



of plumbago inserted in the Annals of Philosophy, vol. i. p. 294, 

 has shown that this residue is of a complicated nature, consist- 

 ing of oxide of iron, oxide ol titanium, silica, and alumina. 



Prom Mr. Mushet's experiments it seems to follow that the 

 compound of iron and carbon, the hardness of which is a 

 maximum, the colour white, and the texture crystallized, is a 

 compound of about 7 atoms of iron and 1 of carbon. Steel, 

 if any confidence can be put in the experiments hitherto made 

 to determine its composition, seems to consist of 1 atom of 

 carbon united with from 10 to 13 atoms of iron, according to 

 the nature of the steel : but these chemical analyses are still 

 too imperfect to permit us to place the different varieties of 

 steel and cast-iron in our table. 



I shall proceed therefore to the salts, many of which have 

 been analysed with great care, and which constitute the best 

 established department of chemical science. 



Genus I. — Sulphates. 



Sulphuric acid, it will be seen from our table {Annals of 

 Philosophy, vol. ii. p. 44), is composed of 1 atom of sulphur 

 and 3 atoms of oxygen, and the weight of an integrant particle 

 of it is 5*000. 



Number of Weight of an 



atoms. integrant particle. 



164. Sulphate of potash 1 s + 1 p 11*000 a 



165. Supersulpate of potash . .2 s + 1 p 16*000 h 



166. Sulphate of soda 1 s + 2 so 20*764 c 



167. Sulphate of ammonia . . . A s + 2 a 7*284 d 



a I found by a careful analysis of sulphate of potash, fused 

 previously in a platinum crucible, that 100 parts of it contained 

 42*2 of acid and 50*1 of potash. Now 5:6:: 42*2 : 50*62; 

 which corresponds with the analysis very nearly. In giving the 

 weight of an integrant particle of the salts I have been obliged 

 to omit the water of crystallization, because it has been accu- 

 rately determined in a very small number of salts only. 



b Dr. Wollaston has shown that in this salt the quantity of 

 acid is just double what exists in the sulphate. 



c According to Wenzel, sulphate of soda is composed of 100 

 acid -f 78*32 base; according to Berzelius, of 100 acid + 



79*34 base. Now 5 : 7*882 :: 100 : 157*64, and ^— = 78*82. 



Now this is the mean of the two experiments. 



rt According to Berzelius (Gillert's Annalen, xl. 282), this 

 salt is composed of 100 acid + 42*561 ammonia. Now 100: 



