Notes on scientific research. 133 



Trabut 1 ) has noticed a peculiar property of cultivated Citrus-species. He has 

 observed that specimens which at first throve well, became etiolated in the second 

 year. Curiously enough, the disease may be communicated by grafting. A diseased 

 wild plant will infect a healthy scion, and conversely a healthy wild tree is infected 

 by being grafted with a diseased scion. So far nothing is known of the origin of the 

 disease. Baur 2 ) has observed a similar peculiarity in the Malvaceae. 



On the distribution of emulsin-like enzymes see p. 21. 



On the distribution of primverin, primulaverin and primverase in the Vegetable 

 Kingdom, see p. 84. 



Chemical Notes. 



It will be remembered that some time ago we referred to a method for the 

 determination of a standard for the unsaturated character of hydroaromatic compounds 

 which has been worked out by J. KHmont and W. Neumann 3 ). 



The first-named author 4 ) has now published details on the method of carrying 

 out this determination. 



W. Ipatieff 5 ) has already on previous occasions published papers on the influence 

 of subsidiary substances on the activity of catalysers. Thus, for example, the catalytic 

 properties of copper oxide or of reduced copper are considerably impaired when 

 hydrogenation takes place in a phosphorbronze instead of in an iron pipe. By using 

 simultaneously catalysers of different action, Ipatieff ) has obtained interesting results. 

 For example, camphor, in the presence of nickel oxide and hydrogen under high 

 pressure at 320 to 350°, is converted in borneol. In order to reconvert borneol into 

 camphor, the former body must be heated with aluminium oxide under high pressure 

 at 350 to 360°. Quite different results were obtained by acting with hydrogen in the 

 presence of both catalysers. 30 grams d-camphor were heated at 200° with 3» grams 

 nickel oxide and 1,5 grams aluminium oxide for 24 hours in a hydrogen-atmosphere 

 under pressure. The reaction-product consisted of isocamphane (m. p. 64 to 64,5°; 

 b. p. 164 to 165°). Carvomenthone afforded pure menthane. ^-Borneol, by the same 

 method, also afforded isocamphane. When ^soborneol was heated at 350 to 360° with 

 aluminium oxide only it yielded crystalline camphene, but the joint reaction of nickel 

 and aluminium oxide led to isocamphane. An altogether different result is obtained 

 when, instead of nickel and aluminium oxide, a mixture of the latter and copper 

 oxide is employed. In that case borneol affords a mixture of solid and liquid camphene. 

 The solid camphene may possibly be contaminated with bornylene. 



Hydrogenation for 24 hours of (2-fenchone in the presence of nickel oxide under 

 pressure at 240° yields fenchenol (b. p. 196°; d 20 o 0,9594; « D + 0) which can only with 

 difficulty be converted into fenchene when aluminium oxide alone is used. The reaction 

 again takes a different course in the presence of nickel oxide and aluminium oxide. 

 Reduction then takes place at as low a temperature as 215°, and is completed within 

 12 to 14 hours, fenchane, b. p. 162 to 163°; di 7 o 0,8766, being formed. 



*) Compt. rend. 156 (1913), 243. — 2 ) Kgl. Preuss. Akad. Wiss. 1906. — ;i ) Pharm. Fast 44 (1911), 5S7 : 

 Report April 1912, 165. — 4 ) Arch, der Pharm. 250 (1912), 561. — r> ) Berl. Berichte 48 (1910), 33S7. - 

 e ) Ibidem 45 (1912), 3206. 



