The Supplement to the Topical Agriculturist 



be sold soon at 2s 6d a pound, and the synthetic 

 product must be able to compete with natural 

 rubber at Is. a pound. The 



ONLY CHEAP RAW MATERIALS AVAILABLE ARE 

 WOOD, STARCH OR SUGAR, PETT10LEUM, AND COAL. 



Wood yields acetone on distillation, but the 

 quantity available is limited and is already 

 in such demand by various Governments 

 for use in making explosives that the price 

 has risen to £90 a to;i, Petioleum and benzene 

 from coal were likewise dismissed for other rea- 

 sons. There then remained inarch and sugar, the 

 former of which can oe obtained cheaply in any 

 quantity. First a complete process was worked 

 out from lactic acid, but it is too complicated to 

 form a paying proposition ; then attention was 

 directed to starch, from which amylic alcohol is 

 prepared. Iso-amyi-ohloridij was prepared, the 

 chlorination being euecced by a special appa- 

 ratus. There are p-.oduccd three dichlorides, 

 which all yield isop :ene when passed over hot 

 soda-lime, so that thay do not require separat- 

 ing. This method was proved ;o yield ezool- 

 lent rubber, but the world's supply ol amy'ic 

 alcohol is limited ; At presaut it is abjut 3 500 

 tons, and costs £140 a ton. To meet this dif- 

 ficulty Professor Fernbacb, of the Pasteur In- 

 stitute, worked out a fracas of fermentation 

 directed to producing d, larger proportion of 

 higher alcohols by usiijg csrti n nitrogenous 

 compounds. After eighteen months*' work he 

 has perfected a rn>bh d which produces not 

 only fusel oil, but acetone. The production of 

 acetone by this peceets is of enormous im- 

 portance, and is expected to bring down the 

 price to a third. The fusel oil obtained con- 

 tains a large quantity of batyric alcohol, and 

 can be made at a cheaper price than £45 

 a ton. The interesting part is that butyric 

 alcohol, from which butadiene is made, is even 

 better than isoprer e as a source of rubber. The 

 process as finally worked out has been checked 

 and confirmed independently by Mr. Otto 

 Hehner. 



Discussion. 



In the discussion satisfaction was expressed 

 at the full justice done to Sir William Xilden, 

 and Sir William referred to the discovery as a 

 great commercial source of wealth to this country 

 and the world. 



Sir William Ramsay— said he could not help 

 feeling how eauy it is to do a thing when you 

 know how, and recalled that in 1874 to 1879 he 

 was working on the pyridine derivatives and 

 employed sodinrn as an oxidising agent in the 

 manufacture of dipyridine. 



Professor Erhardt — of the Badische Anilin- 

 und Soda Fabrik, said, if his memory served 

 him aright, the date of Sir William Tilden's 

 polymerififiou of isopreae had been under- 

 stated. fch;> company began work on the 

 subject three years ago, the result of 

 which will be known shortly through the pub- 

 lished patents. 



Mr. Reid— said that there was no reason 

 why the outpui of turpentine should not be 

 greatly increasod. Russian turpentine only 

 differs from American turpentine in the crude 

 methods employed in its preparation, but from it 



isoprene and butadiene can be as easily produced. 

 He mentioned that he had lately seen a method 

 of great promise of converting heavy residual 

 petroleum into light spirit suitable for motor 

 spirit. The product is an excellent solvent of 

 rubber. 



Dr. R. Messel — said when in Germany a few 

 days previously his attention was drawn to the 

 tyres of a motor-car. Those made of synthe- 

 tic rubber had outworn the Para-rubber tyres. 



Dr. P. Schidrowitz— said the lecture had 

 shown conclusively that the production of pure 

 rubber synthetically is no longer bunkum. The 

 commercial aspects have, however, yet to be 

 considered before certainty can be said to have 

 been attained. 



Professor Perkin — briefly replied. — Chemist <k 

 Druggist, June 22. 



Views of Professor Dutistan. 



To the Editor, "The Times.") 

 Sir, — The accounts in the Press of the new 

 process of obtaining synthetic " rubber " are so 

 wanting in detail and clearness that it is well 

 to draw attention to one important point. 



Although methods of obtaining rubber from 

 isoprene were mentioned by Professor Perkin, it 

 now appears, from published statements, that 

 the principal process consists in obtaining not 

 true rubber from isoprene, but a rubber-like 

 material from a different hydrocarbon known 

 as butadiene. Isoprene contains five atoms of 

 carbon in its molecule, and is convertible into 

 the chibf constituent of true rubber which con- 

 tains in its molecule a multiple of five atoms of 

 carbon. Butadiene, on the other hand, contains 

 only four atoms of carbon, and the rubber-like 

 material obtained from it will, therefore, contain 

 in its molecule some multiple of four atoms 

 of carbon. The material in question is there- 

 fore not identical with the chief constituent of 

 natural rubber, from which it differs in com- 

 position and molecular weight, and is what is 

 known in chemical language as a lower " homo- 

 logue '' of true rubber. 



It is perfectly well-known that homologues 

 exhibit properties, especially physical proper- 

 ties, which differ more or less widely al- 

 though such substances usually bear a close 

 family resemblance. 



The new material may, from the practical 

 point of view, prove to be better or worse 

 than natural rubber, but it is important to 

 point out that it is not the same thing, and 

 that, so far, definite information is wanting 

 as to the respects in which it corresponds 

 with natural rubber in such important pro- 

 perties as resilience, tensile strength, &c. 

 Except for a few observations published by 

 Professor Harpies, of Kiel, we are at present 

 in ignorance of the precise properties of the 

 new substance, which, moreover, has not yet 

 been produced on a large scale. 



Apart, therefore, from the question referred to 

 in your article of yesterday of the cost of pro- 

 ducing the new material in comparison with 

 the cost of producing natural rubber, it is 

 evident that the product of the new process 

 is a new substance, with whose physical pro- 

 perties we are not yet fully acquainted. 



