580 



The Supplement to the Tropical Agriculturist 



Another English periodical now enters the 

 field with proposals relating to the tests which 

 Ceylon citronella oil should be required to meet. 

 It demands that the constants ot the oil shall 

 be as follows : — 



D 15° 0-898 to 0-910, 



ao— 7 to — 13°, 



acid content (calc. as acetic?acid) not to exceed 

 0'25 per cent., 



acetylisable constituents (calc. as geraniol) not 

 less than 58 per cent, soluble in 2 or 3 vols. 80 

 per cent, alcohol ; the solution must remain 

 clear up to an addition of 10 vols. 



With regard to these suggestions we wish to 

 point out that the maximum limit of the sp. gr. 

 should be raised to - 915 at least ; we have 

 occasionally — although very exceptionally- 

 known it to be still higher (up to 920). The 

 maximum limit for the rotation has also been 

 faxed too low, for only recently we examined 

 samples of guaranteed pure oils, expressly 

 distilled for us in Ceylon, which gave only — 

 16°. It would likewise be impossible to main- 

 tain strictly the requirements relating to solu- 

 bility, rather would it be necessary to admit 

 that the diluted solution may turn slightly 

 opalescent, for an absolutely clear solution is 

 an exception. 



In connection with the fixing of constants, the 

 journal referred to also gives a prescription for 

 the determination of geraniol, which, although 

 differing somewhat from that in its precursor, 

 the Chemist and Druggist, shows an equal deter- 

 mination to pass by in silence everything that has 

 recently been published on the subject of the 

 acetylation of citronella oil, and to set up 

 some "special method." There can be no 

 doubt that our own prescription, which is foun- 

 ded upon experimental basis, must be familiar to 

 the English chemists who are concerned in this 

 matter, and it is therefore surprising that in 

 spite of this knowledge they should again per- 

 sist in taking a course of their own. Such a 

 proceeding certainly cannot help the problem 

 forward. We can only repeat again and again 

 that in the case of citronella oil in particular 

 it is necessary to work by a clearly-defined 

 method if it is desired to obtain results which 

 shall correspond to the actual percentage of 

 total geraniol in the sample, and which shall 

 be comparable with each other. In our last 

 Report we gave a detailed account of our 

 method, the trustworthiness of which has been 

 proved by testa with mixtures of known geramol- 

 and citronellal-content, and we may, therefore, 

 content ourselves here with reference to that 

 .Report. It goes without saying that in our 

 laboratories our estimations are exclusively 

 made according to this method, for which 

 reason we refrain from quoting the English 

 methods here. 



Lemok grass Oil. 

 In one of our earlier Reports we described 

 several lemongrass oils produced in the 

 Jalpaiguri District of Northern India. Mr. 

 J. H. Burkill, of Calcutta, who sent us 

 the samples of the oils in question at the 

 time, has now briefly informed us in writing 



that this particular species of grass has been 

 identified since then as C ymbopogon pendulus, 

 Stapf. This information is of particular interest 

 because up to the present only two grasses have 

 been known to produce lemongrass oil, namely 

 C.flexuosus, Stapf, which yields the Malabar oil, 

 and G. citratus, Stapf, the parent-plant of the 

 sparingly-soluble, so-called West Indian lemon- 

 grass oil. The oil from C. coloratus, Stapf, 

 which is also one of the lemongrasses, has only 

 lately become known, and is said to possess char- 

 acteristics resembling those of a mixture of 

 lemongrass and Java citronella oils. 



ARTIFICIAL RUBBER 



is a substance which the chemist can make, 

 even as he can make artificial diamonds ; but 

 during a number of years of experiment the one 

 process has remained nearly as expensive as the 

 other. But no chemist will be surprised to find 

 some mcrning that artificial rubber has been 

 made in a way and on a scale to ensure commer- 

 cial success for the product. There is a report, 

 which we repeat with all the reserve due to a 

 fact that cannot be scientifically verified, that 

 Badische Anilin-und-Soda Fabriken has at last 

 succeeded in making artificial rubber on a com- 

 mercial scale. The "Badische," as it is shortly 

 called, is the greatest of the German chemical 

 manufactories, and the one that is not un- 

 commonly held up by Presidents of the British 

 Association as an example, which the British 

 manufacturer should imitate, of the application 

 of science to industry, it has a staff of a hun- 

 dred chemists, some of whom are engaged in 

 pure research ; and the scope of their work may 

 be inferred from the fact that this organisation, 

 which first wrested the manufacture of the ani- 

 lin dyes from Great Britain, is the origin of the 

 larger number of the modern drugs used in 

 medicine, from phenacetin to sulphonal and 

 adrenalin, It is also the firm which, after spend- 

 ing a quarter of a million of money in chemical 

 experiments, succeeded in making artificial 

 indigo. It is small wonder that anticipation 

 should look to the Badische for the first an- 

 nouncement that the making of indiarubber can 

 now be transferred from the laboratory to the 

 factory. The number of patents known to be 

 associated with the synthesis of rubber that 

 have recently been taken out by the firm has 

 given substance to the idea. 



It will be by no happy accident that the re- 

 sult will be arrived at, but as the conse- 

 quence of patient experiment which is part ot 

 the history of chemistry. The first step was 

 taken twenty years ago or more, when some 

 chemist, untrammelled by any commercial as- 

 piration, found at last what was the essential 

 constituent of caoutchouc— or of indiarubber as 

 we may popularly call it. To Harries belongs 

 the chief credit ; though Greville confirmed his 

 patient analysis by evoking the essential sub- 

 stance "isopreue" from heated rubber. Now 

 '•isoprene," a hydro-carbon, is a chemical com- 

 pound whose molecules are a combination of 

 rive atoms of carbon with eight of hydrogen. 

 The chemist now, so to speak, knew where he 

 was. Hitherto he might have made artificial 

 rubber in his crucibles, hut he would never 



