368 Cittcernlfig the Prlorti^ tf var'mn Difcoveritt. 



xai. 



■HiJIoncal Notes concern'wg the Invention of the Jlr Pump with Metallic Valves ; the Necejfitf 

 of jilioli to produce the cryfallized Salt called Alum ; and the ekBrkal Injlrument tno-wn by 

 the name of the Revolving Dottbler. (W. N.) 



C>iITlZEN ADET, in vol. xxv, of the Annales dc Chimle, p. 165, claims the invention' 

 of an air-pump for Cit. Ami Argand, at Paris, in the year 1776, of which that of Cuth- 

 bertfon is faid to be an imitation. Reference is made to the notes on the third volume of 

 the Lepns Eiementaires de Fh^ique, de Sigaud de la Fond, for a defcription. 



I am happy in this opportunity of doing honour to a philofopher and mechanic, with 

 whofe ability I am well acquainted. That tenacity with regard to the credit arifing fromlirft 

 thoughts or inventions, and the partiality which leads men to exult in the nationality of dif- 

 covery, are eftimable qualities on the whole, becaufe they tend to the promotion of fciencej 

 but they fometimes lead to infinuations oi mala fide; in cafes where the coincidences of rea- 

 foning have alone produced fimilar refults. On this occafion it feems proper to remark, that 

 Mr. Cuthbertfon has candidly difplayed the fource from which he derived his information, 

 and that, upon the whole, it appears highly probable, as well from the refpe£lable charac- 

 ters of the individuals, as from the general circumftances of the cafe, that this artift, as 

 %vcll as Pacts van Trooftwyk, Dr. Rutherford, and Sir George Mackenzie, would have done 

 Juftice to the invention of Mr. Argand, if they had been acquainted with it *. 



In the fame Annales, xxiii. ^2^, there is a claim on the part of the celebrated Chaptai 

 refpeftlng the difcovery of the nature and triple compofition of alum, communicated to 

 the Inftitute by Vauquelin'f. To which this laft chemift has anfwered, in vol. xxv. p. 107, 

 that he was unacquainted with the labours of Chaptai in that refpedt, and had communi* 

 cated his own memoir to the Inftitute a fortnight before Cit. Chaptal's memoir arrived ; 

 and, laftly, that the priority and merit of the difcovery belong to Cit. Pefcroifilles, whofe. 

 Tcfearchcs concerning the nature of alum were publilhed by Berthollct, in his Art of Dyeing, 

 long before that time. 



Another inftance in which I am in fome degree concerned, affords a curious example 

 of the flownefs with which the Improvements of philofophical apparatus are in fome cafes 

 communicated. In the 22d number of the Bibliotheque Brlttannique, there is an account 

 of the doubler of eledrlcity of John Read. The procefs of accumulating eleftricity ;{: by 

 doubling, was invented by Lichtenberg and Klincock, and greatly improved by Bennett, 

 who applied it to Volta's condenfer. In 1787, Dr. Darwin conftru6led a machine for 

 performing the procefs in part mechanically, and in 1788, I made and communicated to 

 the Royal Society the Revolving Doubler by which the whole aft is reduced to the 

 fimple turning of a winch. Five years afterwards, namely in 1793, ^'^- John Read pub- 

 lifted his " Summary View of Spontaneous £le£tricity, &c." in the 4th chapter of which he 



* On this fubjeft, fee our Journal, II. 2S. f Philof. Journal, I. 31 J, 



J Plijlof. Journal, I. 396. 



gives 



