Prertch Nalioval Institute. 275 



the third the worst. M. Scguin, having accurately com- 

 pared their degrees of goodness, that is to say, of tenacity^ 

 has examined the diflerence of their chemical principles. 

 He has aKvavs found in the glue of Paris an insoluhle mix- 

 ture of gelatine and calcareous soapj which is deposited 

 when the glue is dissolved : in that of Flanders, a coagu- 

 lated albumen, which deposits itself also : that of England 

 alone is free from this mixture and deposit. Nothing re-" 

 mained hut lo discover a sure method of making glue si- 

 milar to that of England. 



M. Seguin first saw, that of all the animal parts capable 

 of giving glue, skins furnish the best, and particularly the 

 skins of adult animals killed by the butchers. He then saw 

 that every thing depends on the method of freeing them 

 from the hair. The worst glue is produced by skins freed 

 from the hair by lime ; that of skins freed from the hair by 

 alkalies is a little better ; but the most tenacious is obtained 

 from skins freed from the hair by gallin, and particularly 

 by the successive action of gallin and diluted sulphuric acid. 

 But gallin is rare, and too dear for such an application. 

 M. Seguin, therelbre, did not obtain a complete solution 

 of the problem which he proposed, but by finding out a 

 substitute for gallin, which is moistened malt. 



The name of degras is given to a matter employed for 

 currying leather, and which is obtained in the preparatioii 

 of shammy leather. There are two kinds of it ; that of 

 the country and that of Niorl, which is better and dearer 

 than the former. The degras of the country, according to 

 Seguin, is composed of oxygenated oil, soap, and gelatia 

 in particular states. The two latter principles hurt its ef- 

 fect. The degras of Niort contains none of these sub- 

 stances, and is only oil in a certain state. M. Seguin imi- 

 tates it, the colour excepted, by treating oils with nitric 

 acid ; and the product he obtains proves a substitute, at 

 less expense, for the degras of Niort. 



M. Sage has shown us some singular products of the 

 chemical art in foreian countries. The Chmese make fur- 

 naces which are as light as pasteboard, and which are in- 

 combustible, because they are made of amianthus. Tho 

 same nation employ zinc for coin, a semi-metal which did 

 not seem proper for such a purpose. The Same chemist 

 continues, with indefatigable ardour, to describe those ob- 

 jects interesting to geology which are contained in his col-* 

 lection. He has shown us this vear several curious Ibssils 

 belonging, for tiiG most part, to the class of sb«Us, such wi 

 tcrebratul.'e, oriboceratitefi, numnuiliipiaj &o. 



Ss The 



