202 Messrs. Francis and Croft's Notices of the 



not only does it regain its strength when the circuit is inter- 

 rupted, but it recovers a part of it also, when instead of inter- 

 rupting the circuit the current itself is only slackened*. 



[To be continued.] 



XXXVIII. Notices of the Results of the Labours of Continental 

 Chemists. By Messrs. W. Francis and H. Croft. 



To Richard Taylor, Esq. 

 Dear Sir, 

 "l^E have the honour to forward to you for insertion in 



' your valuable Journal, the accompanying notices of the 

 researches of Continental chemists. We trust that, however 

 brief and imperfect, ihey may prove acceptable to English 

 readers, as but little of what is done abroad, especially in Ger- 

 many, seem i to find its way into England, or, at least, until 

 after the lapse of some years. As instances of this, we need 

 only refer to some papers by English chemists recently pub- 

 lished in the Philosophical Magazine, which in a great mea- 

 sure have been but repetitions of what has been done long 

 since on the Continent. Thus Professor Apjohn would have 

 been spared a great deal of labour had he been earlier ac- 

 quainted with the works of Liebig and Pelouze, and, still 

 more, with those of Mulder. Professor Johnston might have 

 been enabled to shorten his experiments on the Benzoe resins, 

 and probably would have modified his results, if he had known 

 of the researches of Van der Vloet on the same subject, with 

 whose formulae some of Professor Johnston's results agree. 

 Our next communication shall furnish some comparison of 

 these two excellent investigations. The double oxalates, or 

 at least several of them, which have been so well described by 

 Professor Graham in his celebrated paper on the constitution 

 of the Melates, &c. had been described already by Professor 

 Mitscherlich. The fact that aldehyd is contained in nitrous 

 aether, as lately stated by Dr. Golding Bird, was known years 

 before in Germany fi'om the labours of Heinrich Rose. 



It is, however, needless to multiply instances : our object is 

 to assist in preventing their occurrence, and to save English 

 chemists some little unnecessary trouble. It would, it is true, 

 be better to give full translations of the papers, but our own 

 studies do not allow us time for this: — the extracts, which 

 are made in our few leisure hours, are intended to give an 



• See ^. 11 of the Memoir already cited, upon the loss of tension which 

 electromotors undergo when the circle remains closed, and upon tlie re- 

 gaining of the primitive tension when the communication between the 

 poles is suspended. 



