SCJEXCE-GOSSIP. 



347 





CHEMISTRY 



CONDUCTED BY C. AINSWORTH MITCHELL, 

 B.A.OXON.j F.I.C., F.C.S. 



International Atomic Weights.— The Atomic 

 Weights Committee of the German Chemical 

 Society has just issued its report for 1901, in 

 which it has drawn up two tables of atomic 

 weights. In one of these the values are based ujjon 

 Oxygen = 16, and Hydrogen = 1008; and in the 

 other upon H = 1. and = 15 88. The Committee 

 suggests that the former shall be termed " Inter- 

 national Atomic Weights," and be used wherever 

 absolute values are required, as in physico-chemical 

 researches. For the second table (H = 1), which, 

 on the whole, is more convenient, especially for 

 teaching purposes, the title " Didactic Atomic 

 Weights" is proposed. Argon, helium, kryp- 

 ton, neon, thulium (= 171) and xenon find a 

 place in these tables, which include in all 76 

 elements. 



Disadvantages of Aluminium and their 

 Remedy. — The great expectations which were 

 formed of the prospects of aluminium, when first it 

 was obtained at a relatively cheap rate, have, un- 

 fortunately, not been realised. As time went on it 

 was discovered that, contrary to what was first 

 believed, it was readily acted upon by solutions 

 of many salts, by acids, including vinegar, and 

 especially by alkalies, though it excelled copper in 

 the resistance which it offered to nitric acid. To 

 obviate this drawback it is now frequently coated 

 with a layer of silver ; but this in itself is no easy 

 matter, for aluminium is so porous that it retains 

 water and impurities obstinately, with the result 

 that bubbles are formed in the electro deposit, or 

 that this peels off in the polishing process. The 

 chief remedy is to thoroughly cleanse the alu- 

 minium, and to give it a preliminary coating with 

 another metal, preferably copper, before silvering. 

 Several patents have recently been taken out for 

 processes on these lines. Another great drawback 

 to the general use of aluminium is that it has 

 hitherto been very difficult to unite two separate 

 pieces of the metal. This objection, however, will 

 be probably met by the welding process of Heraeus, 

 which has recently been protected in several 

 countries. In this the welding is so complete that, 

 the juncture is practically invisible, and the 

 aluminium can be rolled out to a thin sheet without 

 separating into its component parts. 



Alleged Conversion of Phosphorus into 

 Arsenic. - Some years ago, in an address to the 

 British Association, Sir William Crookes brought 

 forward an ingenious speculation to account for 

 the remarkable relationship which exists between 

 the different elements. He suggested that the 

 whole of these might possibly have been derived 

 from a single primeval element, which as it 

 cooled condensed under recurring conditions 

 (except as to temperature) to form the different 

 substances now known to us as "elements," 



beginning with the lightest, hydrogen, and ending 

 with the heaviest, uranium. This process might 

 be compared to the beats of a pendulum in which 



the elements which condensed ai definite points 

 on the forward stroke wei-e allied in their properties 

 to those condensing at the same points in the return 

 stroke. It was also suggested that this primeval ele- 

 ment might be helium, which bad QOl then been dis- 

 covered, and the existence of which had only been 

 inferred from its absorption lines in the solar spec- 

 trum. Now, in this speculation, for which of course 

 there is no experimental proof, we have something 

 closely akin to the germinal idea of the •■philo- 

 sopher's stone " of the mediaeval alchemists, it is 

 quite conceivable that it is only for the want of suffi- 

 ciently powerful means, i.e. the "lapis philosopho- 

 rum," that we are unable to decompose the bodies 

 we now call "elements*' into their hypathetical 

 constituents or to convert them into one another. 

 In fact, during the last few years more than one 

 claim has been brought forward for such a trans- 

 mutation. The American " argentaurum," which 

 professed to be gold produced from silver, is a case 

 in point, but the examination of the process by other 

 chemists showed that any gold in the final product 

 was there originally. A still more recent instance is 

 the alleged conversion of phosphorus into arsenic, 

 which, as is well known, show many remarkable 

 relationships in their properties. Fittica claimed 

 that when phosphorus was heated with nitre it was 

 partially converted into arsenic. His experiments 

 were repeated by C. Winkler, however, who came to 

 the conclusion that any arsenic found by Fittica 

 must have been present as an impurity in the 

 phosphorus. This is confirmed by Xoelting and 

 Feuerstein, who have recently shown it is not an 

 easy matter to obtain phosphorus absolutely free 

 from arsenic, although the latter can be eliminated 

 b_y distilling the phosphorus twice in a current of 

 steam. 



Alcohol from Sawdust. — It is generally 

 known, especially since the recent investigations 

 into the cause of arsenic-poisoning in beer, that 

 starch is converted into a fermentable sugar, 

 glucose, when treated with dilute acid. Dr. 

 Simonsen, of Christiania. has recently solved the 

 difficult problem of obtaining a similar product 

 from sawdust. Cellulose, which is one of the 

 principal constituents of sawdust, is closely allied 

 to starch, but all attempts to ■■invert" it with 

 sulphuric or hydrochloric acid had previously 

 proved unsuccessful. The first experiments were 

 made with cellulose (paper), which was treated 

 with dilute acid under pressure. The conditions 

 for the best yield of sugar were thus obtained. 

 Then, basing his process on the results of ex- 

 periments on both a small and manufacturing 

 scale, Simonsen succeeded in obtaining about i"J 

 per cent, of fermentable sugar from sawdust, 

 the inversion being made in a closed boiler 

 under a pressure of about eight atmospheres. 

 The sugar was apparently entirely derived from 

 the cellulose, the allied compound, lignin, being 

 unaffected by the treatment. The yield of sugar 

 from pine sawdust was greater than from fir saw- 

 dust, but the largest quantity (about 31 per cent.) 

 was obtained from birch sawdust. Of this sugar 

 about 75 per cent, was fermentable, and the spirit 

 distilled from the fermented liquid was remarkably 

 pure and of good flavour. About 1^ gallon of 

 absolute alcohol was obtained from 12:25 lbs. of 

 sawdust. 



