TRANSACTIONS OF THE SECTIONS. 77 



1 



On the Chemical Composition of some Woods employed in the Navy. 

 By Dr. Grace C.vlvert, F.B.S. 

 The author thought that it mirrht prove interesting to ship-builders if he were to 

 investigate the chemical composition of the various woods employed in the Navy ; 

 especially when this important adjunct of England's wealth is undergoing such 

 extensive modifications, and when it is of such paramount importance to know 

 which is the best wood to bo used in the construction of the new iron-plated 

 frigates. He had examined ten different woods, and the superiority of some foreign 

 woods over English oak could not be too strongly expressed. If English oak has 

 hitherto stood so high, it must have been owing to our ignorance of the valuable 

 properties of some of the woods gTOwn in tropical climates, in which the soluble 

 and highly decomposable tannin of oak is replaced in some instances by resins, and 

 in others by substances similar to caoutchouc. This is the case with Moulmein 

 teak', Santa Maria, Moira wood, and Honduras mahogany, which gives to them a 

 great advantage over oak for iron ship-building. Thus he has found that in tho 

 same time, and under similar circiuustances, oak will attack iron twice and three 

 times as rapidly as the woods above-mentioned. He has also remarked that if cubes 

 of the same dimensions of the various kinds of wood remain in contact with water 

 for five months, they lose respectively tho follomng per-centages of their sub- 

 stance : — Unseasoned oak, 24 ; seasoned oak, 12 ; iSJiican teak, 3^ ; Moira wood, 4 ; 

 Honduras, .3; Santa Maria, 1-G; Greenheart, 5-6; Moulmein teak, 1-7. The 

 facility of mildewing or decaying is as follows : — Unseasoned oak, rapid ; seasoned 

 oak, much less : Afi'ican teak and Honduras mahogany, limited ; Moira wood, Santa 

 Maria, and Moulmein teak, none. For fiu-ther details Mr. Grace Calvert woidd 

 avail himself of an early opportunity of publishing a complete paper ; but there 

 was one point which he deemed it his duty to mention at once. During his 

 researches he had found a great difference between oak" felled in summer and that 

 felled in winter, viz. that the oak felled in winter was rich in tannin, while the 

 oak felled in summer contained little or no tannin, but a large quantity of gallic 

 acid ; and on examining some specimens of wood from unsoimd gun-boats furnished 

 to him by some of Her Majesty's Officials, he found that tho chemical composition 

 of the wood of the soimd gun-boat was identical with that of well-seasoned oak, 

 while the composition of the wood of the imsoimd gun-boat was identical with that 

 of unseasoned summer-felled oalc. 



On the Chemical Composition of Steel. By Dr. Ceace Calteet, F.E.S. 

 Tho author entered into some detail respecting tho interesting discussion 

 which has lately taken place before the French Academy of Science, between 

 MM. Fremy and Garon, on the chemical composition of steel, the former contend- 

 ing that nitrogen is essential to the conversion of iron into steel, the latter that 

 carbon alone is sufficient to effect that object. But an observation that Mr. Grace 

 Calvert has made, tends to show that the molecular condition of steel has a great 

 deal to do with^the nature of its chemical composition ; for if a piece of soft steel be 

 divided into two portions, and one of these is hardened or highly tempered, the 

 slow action of acetic acid proves to be quite different ; and whilst soft steel is scarcely 

 acted upon by weak acetic acid, hard steel is rapidly dissolved. Further, the soft 

 steel leaves a homogeneous gTey carburet of iron, similar in its texture to the gTa- 

 phitoid compoimd lately described by him (Mr. Calvert), whilst that of tempered 

 steel is black, possesses no cohesion, and has the appearance of pure carbon. 



On the Evolution of Ammonia from Volcanos. 

 By Professor Daubent, M.D., F.B.S. 

 This phenomenon had been ascribed b}' Bischof to the decomposition of bitu- 

 minous matters by volcanic heat; by Buusen to the lava flowing over herbage, and 

 disengaging its nitrogen, which exhibited itself in the form of ammonia ; and on 

 former occasions, by tho author of this paper, to the direct union of hydrogen and 

 nitrogen in the interior of the earth under an enormous pressure. Now, however, 

 that Wtihler has shown the affinity which subsists between nitrogen and certain of 

 the metals and simple combustibles, somo of which, as titanium or boron, combine 

 with it dii"cctly with such avidity that the union is attended with combustion j 



