Royal Societtj. 245 



finer than those of the anterior roots. The anterior roots are at- 

 tached to the anterior parts of the antero-lateral columns, which they 

 traverse horizontally in straight bundles, till they reach the anterior 

 horns, in which they break up and form a complicated network. 

 The author has not yet been able to determine whether any of the 

 fibresof the spinal nerves ascend with the longitudinal white columns. 



December 12. — Sir Frederick Pollock, V.P., in the Chair. 



, . A paper was read, entitled, " On the Action of Nitric Acid on 

 various Vegetables, with a more particular examination of Spartium 

 scoparium, Linn., or Common Broom." By John Stenhouse, Esq., 

 JF^K.S. Received November 18, 1850. 



',n This paper is a continuation of a series of investigations intended 

 to elucidate the nature of vegetables by means of chemical reagents. 

 A preceding paper contained an account of the eftects produced 

 by the action of sulphuric and hydrochloric acids on the matiere 

 incrustante of several plants belonging to different great classes of 

 vegetables. The effects of nitric acid upon a variety of vegetable 

 groups are now described ; the researches having been undertaken 

 in the hope that by means of this powerful reagent some light might 

 perhaps be thrown on peculiarities in their respective constitutions. 

 The first plant experimented on with this view, was the Populus 

 balsamifera, as i-epresenting the numerous family of the Poplars. A 

 quantity of the smaller branches of this tree, cut into pieces, was 

 exhausted with boiling water. The dark-coloured bitter-tasted liquid 

 which it yielded was evaporated to the state of an extract, which 

 was digested for nearly twenty-four hours with dilute nitric acid. 

 This strongly acid solution was evaporated to dryness on the water 

 bath, the dried residue was dissolved in a considerable quantity of 

 hot water, and the solution after cooling was carefully filtered. The 

 clear liquid, after concentration to a very moderate bulk, was exactly 

 saturated with carbonate of potash. A yellow crystalline sediment 

 quickly appeared. It consisted of nitropicrate of potash, and the 

 potash salt of a new acid, to which the author has given the name of 

 nitropopulic acid. The mixed potash salts were then collected on a 

 filter, dried by pressure, and were treated with a cold solution of 

 dilute carbonate of potash, which readily dissolved out the nitro- 

 populate of potash, while it left the nitropicrate of that base unacted 

 on. The two salts were then separated by filtration, the nitropi- 

 crate remaining on the filter, while the nitropopulate was dissolved 

 in the alkaline liquid. The solution was next slightly supersaturated 

 with hydrochloric acid, when the nitropopulate of potash precipi- 

 tated as a compact crystalline powder, which was purified by re- 

 peated crystallizations out of hot water. When pure, the potash 

 salt, which crystallizes in small lemon-yellow prisms, is boiled with 

 a considerable excess of hydrochloric acid, and, on the cooling of 

 the solution, the nitropopulic acid is deposited in silky needles, 

 forming concentric groups of a pale yellow colour. By digestion 

 with animal charcoal, the nitropopulic acid is rendered perfectly 



