52 KBPORT — 1856. 



method complained of to be absolutely correct ; but be feared that tlie semi-scientific 

 and the general public were deceived by it, and that chemists also often came to 

 believe there was some truth in their own arbitrary mode of expressing the results of 

 analysis. 



Notes on Nitroglycerine. By J. H. Gladstone, Ph.D., F.R.S. 

 The author had made several observations on this remarkable explosive li(^uid, 

 \vliich had been iirst exhibited by Dr. De Vrij at the Ipswich meeting of the Associa- 

 tion ; but the recent research of Mr. Railton had forestalled him, and left little for 

 him to bring before the public. However, he felt convinced that nitroglycerine was 

 not always uniform in its properties, and was perhaps various in its composition. 

 Tlius a liquid produced by immersing glycerine (in the hydrated state in which it is 

 found in commerce) in a mixture of one part of fuming nitric acid and three parts of 

 sulphuric acid, was found to be easily exploded by a blow with a hammer, or when 

 heated rather strongly in a test-tube, giving rise to much flame and noise, with the 

 evolution of much nitrous gas ; while a liquid produced in a precisely similar manner 

 from the same glycerine, but after it had been rendered anhydrous, did not explode 

 by a blow with a hammer, and burnt without noise when very strongly heated. 

 Again, some explosive nitroglycerine was allowed to decompose spontaneously till only 

 about one-half was left; this remaining portion was non-explosive. Each variety, 

 when exposed to a bath of solid carbonic acid in alcohol, froze, becoming at first viscous, 

 and then assuming an appearance similar to that of the fatty acids at the ordinary 

 temperature. This substance, like other nitrous acid substitution products, is liable 

 to slow spontaneous decomposition. This had been several times observed : one spe- 

 cimen exposed for some weeks to the light of the summer sun, gave off abundance of 

 red fumes, and separated into two liquids, between which long crystals of oxalic acid 

 formed. The upper liquid contained the products of decomposition, being in fact 

 an aqueous solution of nitric and oxalic acids, with a large quantity of ammonia, a 

 little prussic acid, and traces of two or three slightly acid or neutral bodies, which 

 coidd not be identified. 



On the Conversion of Tannin into Gallic Acid. By John Hoesley. 



It is several years since I first noticed the facts which 1 now bring before j'our 

 notice. I have never yet heard or read cf the practical application of the agent in 

 the manufacture of gallic acid in the manner I now suggest. 



Every chemist is aware that the quantity of gallic acid naturally contained in the 

 gall-nut is very small compared with the tannin (alias tannic acid), and that the gallic 

 acid of commerce is a manufactured article, being obtained by what is called the fer- 

 mentation process, which consists in the saturation of the braised galls with water 

 and exposing the mass to the air for a period of several weeks or even months, when 

 decomposition sets in, a mould collects, and small yellov.' crystals of gallic acid are 

 observable, evidently the result of the oxidation of the tannin. The gallic acid is 

 then dissolved out by boiling the mass in water, and crystallizes from the concentrated 

 liquid on cooling. 



It occurred to me to make experiments by keeping powdered galls in contact for 

 some time with liquid acids, such as sulphuric, sulphurous, nitric, and acetic acids, 

 but with diluted sulphuric acid only did I perceive any change produced ; small 

 •white tufts or nodules of gallic acid being observed soon to protrude themselves, so to 

 speak, to the surface of the dried cake, 



I have lately, for the purpose of drawing up this paper, made further experiments, 

 of which these are specimens. I merely moistened the powdered galls with the diluted 

 acid and exposed the mixture in an evaporating dish to the full action of the sun, and 

 in a few hours signs of intestine motion began to manifest themselves and crystalline 

 white tufts were forming ; these white tufts gradually increased from day to day, and 

 became more apparent as the mass dried. It is necessary to renew the application 

 of moisture from time to time, so as to promote the growth of gallic acid. 



In proof of the above, I likewise treated ^?»-e tannin by triturating it with dilute 

 sulphuric acid, and in a very short time white crystalline tufts of gallic acid were 

 visible. 



