EleBive Attra^ions of thi Earths i 419 



have {'aid of man walking in an inclined or horizontal plane. His memoir is concluded 

 by the confideration of the labour ol men employed to cultivate the ground. He has 

 found by experience, that the whole q^uantity of aftion tlms afforded during a day 

 amounts to too kilograms (22olb.j elevated to one kilometer. 



Afterwards comparing this work with that of men employed to. carry burthens up an 

 afcent or fteps, or at the pile engine, he finds a lofs of about ^%- part only of tlre~ 

 quantity of aflion which may be neglefled in refearches of this kind. 



The author takes great care to warn readers againfl experiments of top fhort duration, 

 and in feveral places fpeaks of the error to which we areexpofed by making experiments 

 with men of more than common ftrength. The mean refults have alfo a relation to the 

 climate. " I have caufed," fays the author, " cxtenfive works to be executed by the 

 troops at Martinico ; where the thermometer is fcldom lower than twenty degrees; I 

 have executed works of the fame kind by the troops in France; and I can affirm that 

 under the touiteenth degre of latitude, where men are almofl always covered with 

 perfpiration, they are not capable of- performing half the work they could perform in 

 our climate." 



• XI. 



New Refearches into the Affinities which the Earths exert upon each other in the humid 

 and in the dry way. By Citizen Guyton.* 



I 



T was not even fufpefted in the earlier times of chemiftry that an eleflive attraftion 

 could be exerted between two pure earths. Their union was thought to be the confe- 

 quence of a fortuitous aggregation, a hmple adhefion referable neither to eleflive 

 attra6lion nor the equilibrium of compofition. But when it was obferved that two 

 earths infufible fmgly in our furnaces, fuch as filex and lime, were fufed together with 

 conliderable facility into an homogeneous matter, of which the principles could no more 

 be feparated unlcfs by chemical methods ; it became necefTary to admit of a mutual 

 aftion which became aftive as a certain temperature, that is to fay, a true chemical 

 affinity. 



The firfl ffep being made, it feems as if chemifls would not have delayed to multiply 

 their proofs by direfl experiments ; but it is neverthelefs true, that very few fafts are yet 

 eflablifhed in the dry way, and that it begins to be found neceffary to interrogate nature 

 in the humid way, of which the procefTes are fo much the more important, as they more . 

 nearly approach the very methods ufed by nature to form thefe earthy compounds, which 



* Extrafled from a Memoir, read at the fitting of the National Inftitute of France on the j6 prairial laft, 

 (June 3, 1799,) infertcd in the Annales de Chimie xxxi. 246. 



confiflipj^ 



