SCIENCE- GOSSIP. 



CHEMISTRY 



CONDUCTED BY C. AIXSWORTH MITCHELL, 

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



A Coffee without Caffeine. — The stimulating- 

 properties of tea and coffee are cine to the presence 

 of the alkaloid caffeine, which in ordinary coffee- 

 berries amounts to about 1*5 per cent. Bertram! has 

 recently analysed the berries of C. Immblotiana, 

 which grows in the Comoro Islands, and has found 

 that they are absolutely free from caffeine, and 

 hence he considers that there is no doubt as to this 

 plant being a distinct species. 



" Fermentative " Action of Platinum. — 

 Finely divided platinum can convert alcohol into 

 acetic acid by an oxidising process closely resem- 

 bling the fermentation of wine into vinegar by the 

 acetic bacteria. Bredig has shown that there is 

 a further remarkable resemblance, for many 

 poisons, such as prussic acid, temporarily destroy 

 the " fermentative " power of platinum ; whilst 

 iodine is so toxic that the oxidising power is not 

 regained after complete removal of the iodine. 



Alcohol from Sawdust. — In reference to your 

 note on " Alcohol from Sawdust " in April Science- 

 Gossip, I may mention that the conversion of 

 cellulose into dextrose, capable of fermentation, is 

 not by any means new, though I have not heard of 

 cellulose in the comparatively impure form of 

 sawdust being successfully treated hitherto. By 

 the bye, is the use of the word " invert " justified 

 in this connection ? Strong H..SO.,, with subse- 

 quent dilution and boiling, converts dry cellulose 

 first into dextrin and then into dextrose, which 

 may be obtained as a syrup by neutralising with 

 chalk and then filtering. I have in my laboratory 

 a small quantity of dextrose that I made some 

 years ago from Swedish filter paper, the purest 

 form of cellulose known to me, but which I have 

 unfortunately allowed to grow mould} 7 . The pro- 

 cess is, however, not quite as simple as it sounds ; 

 but I found the subsequent fermentation into 

 alcohol the most difficult, owing, I believe, to the 

 want of proper " food." I have sometimes thought 

 of digesting sawdust with certain solvents to get 

 rid of the resinous matters, or of experimenting 

 with wood cellulose in the comparatively pure 

 form of sulphite pulp, but anticipate difficulty with 

 the lignin.— F. SMllington Scales, 7 The Elms, 

 Sunderland. 



[The word " inversion " as applied to starch and 

 cellulose is literally incorrect, but it is a convenient 

 term in common use to describe the bydrolyses 

 effected by acids in the same way as the inversion 

 of cane sugar. The fact that sugar could be obtained 

 by the action of acid on cellulose was recorded in 

 1819, but the details of any manufacturing processes 

 based on this were kept secret. Dr. Simonsen 

 found that the yield of fermentable sugar that could 

 be obtained from pure sulphite cellulose varied 

 sireatly with the strength of acid, pressure and 

 other factors. The most favourable conditions 



were: — 40 grammes of cellulose, with 1,080 cc. of 

 dilute sulphuric acid, containing 0'45 to - 6 per 

 cent, of anhydrous acid, and a pressure of 8 to 

 10 atmospheres. The maximum yield was 43T 

 per cent, of sugar on the weight of cellulose taken. 

 —Ed. Chemistry, S.-G.] 



Trafalgar Square Well Water. — It is very 

 interesting to compare the results of analyses of the 

 Government well in Trafalgar Square, London, as 

 made by different chemists since 1846. These have 

 been tabulated by Mr. W. W. Fisher, M.A., F.I.C., 

 with the object of showing the variation in the 

 water during the last fifty years. The following 

 tabulation, which is published here with Mr. 

 Fisher's permission, shows the constituents in 

 parts per hundred thousand : 



a 5 i t. i 2 i i 



° $ V ib e» cb 

 '- -^ >ra co co co 



Mag- 

 nesia 



MgO 



1-66 



1-56 



1-40 



Hard- 

 ness] 



1-50 



Lime 

 CaO 



O) r-c CC |] O 

 Ol CS Oi ^ cs 



£ £ -5, < s* f^ 





■ 

 Silica 



SiO, 



Z 2 * 1 2 



cU 8 



C3 O CO I CO 

 C ~V CC r-i 





- ~. C5 — »0 





14-4 



99-15 



84-97 

 83-40 



85-7 



Q 



184G 

 Brando 



1848 



Abel and Rowney 



Q. J. Chem. Soc. I. 97 



1857 



Campbell 



Q. J. Chem. Soc. IX. 22 



1869 



Frankland 



Riv. Poll, Com. 



VI. Report 



1900 

 W. W. Fisher 



It appears that between 1848 and 1857 the water 

 lost 14 per cent, in total saline constituents, but 

 since the latter date its composition has remained 

 practically constant. This loss consisted in- the 

 main of potassium oxide and carbonic acid. 



Tung Oil. — This remarkable oil-, which is also 

 known as Chinese wood oil, is expressed from the 

 seeds of the Aleurites cordata. It is extensively 

 employed in China and Japan in the manufacture 

 of varnish, but recent attempts to introduce it into 

 Europe as a commercial article have met with only 

 partial success. It possesses greater drying pro- 

 perties than any other known oil, far exceeding- 

 linseed oil in this respect. On being heated in a 

 vessel from which the air is excluded, it undergoes 

 a curious change, being converted into a solid mass. 

 The purified fresh oil has a not unpleasant odour, 

 but the smell of old or less-refined oil is very dis- 

 agreeable, and has prevented its general use in the 

 linoleum industry. 



