84 Biographical Account of the late John Dalton. 



name of Stechiometrie. This work was founded on the following pro- 

 position, which llichter had established by numerous experiments. 



If two neutral solutions of salts are mixed together, supposing them 

 such that mutual decomposition ensues, the new salts formed will be 

 equally noutral with the original salts. Thus, suppose we mix together 

 solutions of nitrate of barytes and sulphate of potash, two new salts will 

 be formed, namely, sulphate of barytes and nitrate of potash. These 

 two salts will be as neutral as the original salts from which they are 

 derived. And if we employ the original salts in the requisite proportions, 

 the decomposition will be complete. We have only to employ 16 J nitrate 

 of barytes and 1 1 sulphate of potash to accomplish this object. This 

 fact had been observed by chemists before the time of llichter, but he 

 was the first who drew from it the conclusion to which I wish to call 

 your particular attention. llichter reasoned on it, in the following 

 manner : — 



The quantity of two alkaline bases which are necessary to neutralize 

 equal quantities of an acid, are, in the proportion of the quantities of the 

 same bases, necessary to neutralize any other acid. Thus if 4 soda and 

 6 potash neutralize nitric acid, we must employ the same proportions of 

 these bases to neutralize any other acid. The soda in phosphate of soda 

 will be to the potash in phosphate of potash as 4 to 6. And the same 

 will apply to every compound of potash and soda, with any acid whatever. 



Suppose we have sulphuric acid, nitric acid, and potash, and soda. If 

 we know the composition of sulphate of potash, and sulphate of soda, and 

 also of nitrate of potash, then we can determine the composition of nitrate 

 of soda by calculations. 



Hence it follows that figures may be attached to every acid, and every 

 alkali, indicating the quantity of each necessary to saturate the quantities 

 of every other acid or base indicated by the numbers attached to it. 

 The whole of Kichter's time from 1792, till his death, about the begin- 

 ning of the present century, was occupied in endeavouring to determine 

 these numbers by experiment. He published a variety of tables showing 

 their numbers. But his views were so obscured, by opinions which he took 

 up concerning certain arithmetical ratios in which they stood to each 

 other, that it is very difficult to peruse his papers ; and as his experiments 

 were not very accurate, his views were very generally neglected, except 

 by Berzelius, who devoted about eight years to the repetition and cor- 

 rection of these analyses of llichter. 



Fischer showed that all the tables of llichter might be reduced to one, 

 indicating the saturating power of the acids and bases examined by him. 

 Sulphuric acid was reckoned 1000, and all the acids and bases were re- 

 ferred to that number. It will, perhaps, be better if we reduce them to 

 our present scale, in which oxygen is represented by 1. Beside Kichter's 

 table I shall place the atomic weights of these bodies as they have been 

 determined by the latest and most accurate experiments. 



