160 MEMOIK OF DR. DALTON, AND 



affinities, but neither knew the other's results, and both 

 were lost sight of. The one (Ritcher) did not know that 

 he had got close upon a universal law, the other (Kirwan) 

 did not know that he had got the mode of expressing that 

 universal law, but used it for what it was little worth, an 

 expression of affinity. 



We now come to Wenzel, one of those men whose names 

 have been brought forward as a much neglected philosopher, 

 and to whom almost every writer on the history of science, 

 who has had occasion to mention him in later years, has 

 been anxious to award the due honour. We see his book con- 

 stantly quoted. Some writers give us his words, others give 

 us what appears such a clear explanation of his ideas that 

 we feel no more to be wanting. I had been long anxious to 

 obtain his works, but after advertising in Germany, and 

 inquiring in several towns and large libraries in this country, 

 as well as in France and Germany, I did not obtain the 

 volume, and proceeded without it. I afterwards found that a 

 duplicate copy existed at the Munich Royal Library, and was 

 fortunate enough to obtain it, duplicate copies being generally 

 disposed of. Having read it carefully over, I found no such 

 passages as are imputed to him ; and, therefore, read it still 

 more carefully again, and then a third time, but they did not 

 exist. Having written to two eminent historians of science 

 for an explanation, I find that neither had seen the volume; 

 but one of them informed me that the mistake had been 

 rectified in a supplement to the " Handwoerterbuch der 

 Chemie u. Physik."* 



The reciprocal saturation which results when two salts 

 decompose each other, is the discovery, the honour of which 

 has long been given to Wenzel. It is a curious fact that not 

 only does he not see this, but he sees and explains the con- 



• It is by Dr. J. S. C. Schweigger, and has been since published as a 

 pamphlet (Ueber die Stocchiometrische Reihen im Sinne Richter's), &c., 

 Halle, 1853. 



