the «cbaeic 

 acid. 



154 ARTIFICIAL STONED 



Heof deoxuling indigo. Mr. Bouillon-Lagnmgc has ascribed 

 to the suberic acid a property, that belongs to the bitter 

 yellow matter, which forme a green by mixture with the 

 blue of the indict). It is this too, that turns a solution of 

 copper green; for I have satisfied myself, that the white 

 acid merely dilutes the blue colour, just as an equal quan- 

 tity of water would have cone. 

 Analopt;* to From what has been said I conclude, that the suberic 

 acid has great analogy with the sehaei-, with which Mr. 

 Thenard has made us acquainted * ; and that the only strik- 

 ing difference between them is the crystalline form, which 

 the suberic acid assumes when diffolved in water or m 

 alcohol. 



XVI, 



Method of Fabricating artificial Stone employed in the Vici- 

 nity of Dunkirk. By Mr. Bertha nd, Apothecary to the 

 Army of the Coast]', 



Method of •**- HE materials employed for this purpose are the ruins 



xnakiig artifi- f the citadel, consisting of bricks, limeJand sand. These 

 cial stone in . , , « •„ ,. , n 



Fiance. are broken to pieces by means ot a mill, formeq ot two 



stone wheels, following each other, and drawn by a horse. 

 Water is added; and the matter, when well ground, is red- 

 dish. This is put into a trough, and kept soft by means of 

 water. 



When the trough is full, some lime is burned, and slack- 

 ed by leaving it exposed to the air, and this is mixed in the 

 proportion of one eighth with the cement above. 



A wooden mould is laid on the stone, and after a thin layer 

 of sand is thrown on the stone, to prevent the cement's ad- 

 hering to it, a layer of cement is poured in, and on this a 



• See Journal", tol. I, p. 34. 

 f Annales ds Chimie, rol. LV, p. 285, 



layer 



