M. Hess on the Scientific Labours of Richter. 87 



of calcium by sulphuric acid, and infers the quantity of lime 

 to be found in the hydrofluate from the quantity contained in 

 the sulphate. He thus finds by analysis, that 1000 parts of 

 hydrofluoric acid require 1882 of lime for their saturation ; 

 by synthesis he finds 1865 parts. After that, he finds that 

 the same quantity of acid was saturated by 3797 parts of 

 potash, and continues in these terms : " It has been shown 

 (he speaks of his Stochiometrie) that the quantities, whether 

 of alkali, or of alkaline earth, which served to saturate the 

 same quantity of one of the three volatile* mineral acids, 

 were in constant relation with each other." Richter then ex- 

 amines whether the results which he has just obtained sup- 

 port this proof: he had before found that 1000 parts of mu- 

 riatic acid require 1107 parts of lime for perfect saturation, 

 and 2239 of potash. For hydrofluoric acid he had obtained 

 1882 parts and 3797. But 1107 : 2239 sfe 188.2 : 3807, which 

 differs very little from the result of the experiment. 



A happy and important discovery is not all; the consequences 

 of it must be felt; the promptitude of intelligence must go 

 beyond the tardiness of experience, for it is only in this future 

 that we can be armed against all the shackles of the present. 

 Now this is the manner in which Richter announces and 

 extends the consequences of his experiments (vol. iv. p. 67, 

 year 1795). When two determining {determinants) elements 

 (i. e. two acids,) each taken at the rate of 1000 parts, are satu- 

 rated by the substances a, b, c, d and a, |S, 7, 8, so that each 

 time a and a, b and /3, &c. are always the same substance ; 

 in this case the (substances) quantities a, b f c are among them- 

 selves absolutely in the same relation as «., /3, y. 



This theorem of Richter's is a true touchstone for all ex- 

 periments which relate to neutrality ; for if the results do 

 not agree with this principle, they must be rejected without 

 hesitation. But, he adds, although according to the announce- 

 ment of the principle we may use relations known and deter- 

 mined by experiment, in order to find others by calculation, 

 it will always be useful to verify these last by the fact, for we 

 gain by it, after having recognised certain relations, the means 

 of verifying the numbers themselves from which we had set 

 out, and thus to correct the little inaccuracies by which they 

 might be affected. 



Richter then points out the work to be done ; but in order to 

 feel all the importance there is in its being done with the greatest 

 precision, it will suffice to tell you that he forms a plexus of 

 number, which covers the entire domain of chemical researches 

 whatever they may be, and that it is precisely from not having 



* By these he understood the sulphuric, nitric and muriatic acids. 



