542 Intelligence and Miscellaneous Articles. 



of the exposure in advance of the other side not coated in the battery. 

 I have tried this with a great variety of solutions, and always with 

 the same result. 



I am, Gentlemen, 



Your most obedient Servant, 



William E. Kilburn. 



ON THE ACIDS OF PINES. BY M. AUG. LAURENT. 



Pinic and sylvic acids were first analysedbyM. Rose, who gave as 

 their formula C-*" H^^ O', their salts being represented by G-"^ H^* 

 0* + M'-0. More recently M. Liebig has shown that sylvic acid 

 contains C*° W'"^ O*, and M. Laurent states he has found that pinic 

 acid has the same formula. 



M. Laurent, on examining six or seven years since the resin which 

 flows from the Pinus maritima of the heaths of Bordeaux, met with 

 a new acid which he called pimaric acid, and which possesses the 

 same composition as the preceding. When pimaric acid is distilled 

 in vacuo, it is converted into pyromaric acid, without change of com- 

 position ; and eventually this same acid, when crystallized and left to 

 itself, undergoes an isomeric modification, and is converted into 

 amorphous uncrystallizable pimaric acid. 



The salts of all these acids are represented by the following for- 

 mula, C""^ H<'0 O^ + M- O, which does not agree with opinions en- 

 tertained by the author and M. Gerhardt. 



These salts should contain, either C'o H^s M^ O*. or C*" H^^ ^-2 

 O^ ; the salts examined by MM. Rose and Laurent are those of sil- 

 ver and lead. As it would have been difficult in a fresh analysis of 

 these salts to determine whether they contain H- O more or less, the 

 author endeavoured to ascertain whether the preceding acids, on 

 combining with anhydrous oxides, did or did not disengage water. 

 For this purpose jiulverized sylvic and pimaric acids were mixed with 

 recently fused and pulverized litharge. The mixture, introduced into 

 a glass drying vessel, was heated in a current of dry air ; a small 

 quantity of w-ater, amounting to about one-third of an atom, was 

 disengaged. Presuming that the contact of the acid and the oxide 

 was not sufficient, a little aether was poured on the mixture, and it 

 was heated to 284° F. 



rOOO gramme of fused pimaric acid lost 0'028 of water. 



I'OOO gramme of fused sylvic acid lost 0-034 of water. 



1*000 gramme of fused pimaric acid, heated alone to 284°F., lost 



1 milligramme. 



1000 gramme of fused sylvic acid, heated alone to 284° F.,lost 



2 milligrammes. 

 According to the formula — 



C-io 3000-0 



H58 362-5 



H2 112-5 = 300 



O' 3000 



3775-0 



