establish the First Principles of Chemistry by Experiment" 451 



Dr. Thomson has found reason to adopt an idea, suggested 

 some years ago by Dr. Prout, that the numbers which express 

 the atomic weight of bodies are multiples by a whole number 

 of the atomic weight of hydrogen ; and his favourite object, 

 visible in almost every page, is to prove the coincidence to be 

 perfect. In this attempt ne has been so successful, that the 

 correspondence between his hypothesis and the result of his 

 experiments is startlingly precise. As the accuracy of his re- 

 sults, which, if true, are very important, can be duly estimated 

 only by an analyst of extensive experience, we looked forward 

 with impatience to hear the opinion of Berzelius. His opi- 

 nion has at length reached us ; and as it is expressed in lan- 

 guage extremely strong and extremely unusual, we think it 

 necessary to employ his own words. We have accordingly 

 translated a few passages from the Yahres-Bericht for 1827 

 (Woehler's Translation). 



" This work belongs to those few productions from which 

 science will derive no advantage whatever. Much of the ex- 

 perimental part, even of the fundamental experiments, appears 

 to have been made at the writing-desk^ and the greatest civi- 

 lity which his contemporaries can show its author, is to forget 

 that it was ever published." (page 77.) 



" Thomson has published an essay • On the method of 

 analysing sulphate of zinc ;' a subject scarcely requiring, one 

 would think, a separate essay, since the composition of this 

 salt is known with considerable certainty. The great im- 

 portance attached to it is owing to the circumstance, that in 

 his large work on the atomic weights and chemical propor- 

 tions, the analysis of this salt is the basis on which the whole 

 superstructure is founded. In describing this analysis, Thom- 

 son states that the oxide of zinc was precipitated by carbo- 

 nate of soda, and that 18*125 grains of crystallized sulphate 

 of zinc yielded 8 grains of anhydrous neutral carbonate of 

 zinc. In this fundamental analysis are two errors -—errors of 

 such a nature as it is difficult to commit, and which appear 

 to prove that the results were invented. Some one had told 

 Thomson that his whole work was of little value, because, in 

 the fundamental experiment, the zinc was precipitated by car- 

 bonate of soda in the cold. To this privately communicated 

 remark, Thomson openly replied, That he had supposed 

 chemists would have given him credit for a knowledge of the 

 mode of separating oxide of zinc from acids, and had there- 

 fore omitted details ; but as he found this opinion erroneous, 

 it became necessary to publish a full account of his process. 

 Ninety grains (five atoms) of sulphate of zinc were precipitated 

 by carbonate of soda, and yielded from 29*3 to 31*03 grams 



3 M 2 of 



