



I 







per cent. 



[deh 



yde I . . 



. . — 



» 



II . . 



. . — ; 



» 



Ill . . 



. . — 



M 



IV . . 



. . 0.06 





Schimmel $ Co. 



IV 



material burnt 



chlorine 



per cent. 



g- 



per cent. 



0.18 



3.26 



0.44 



0.08 



3.06 



0.13 



0.12 



3.46 



0.33 



4.05 



0.26 



Chemical Preparations and Drugs. 57 



The just-described method will, we think, remove a difficulty which has meanwhile 

 made itself very much felt. The uncertainty of obtaining a benzaldehyde really free 

 of chlorine in a commercial way had become intolerable since preparations had been 

 put on the market labelled "technically free of chlorine". The qualitative test was 

 sufficient to show that these materials still contained very considerable amounts of 

 chlorine (compare table above) ; yet these materials found buyers when the sellers had 

 sufficient audacity to assert that their product did not contain more than 0.02 per cent, 

 of chlorine, which was accepted as the maximum permissible contents of an aldehyde 

 "technically free of chlorine". Up to the present they might risk such bold assertions 

 in the knowledge that most analytical chemists were not in a position to establish 

 the chlorine contents beyond doubt. As a striking proof for the correctness of this 

 assumption we give the following summary of data placed at our disposal; they 

 concern the amounts of chlorine found in 4 different commercial laboratories in four 

 different samples of benzaldehyde. Our retesting by the method described gave in all 

 the four samples chlorine percentages which exceeded the double values found by 

 other methods. Laboratory 



ii in 



per cent. per cent. 



0.01 0.19 



0.02 0.11 



Since we can burn any desirable quantities of benzaldehyde in the manner described, 

 even low chlorine contents may accurately be determined, and it is now really possible 

 to identify a benzaldehyde free of chlorine as such. Our experiments demonstrate that 

 the limit of sensitivity is about 0.005 per cent, of chlorine. When the values go below 

 that, the consumption of silver nitrate, amounting only to a few drops, will be too 

 small to give reliable results, all the more so, because bitter almond oils of our own 

 manufacture (see page 56), both containing prussic acid and free of prussic acid, the 

 absolute freedom from chlorine of which we were able to guarantee, consumed a few 

 drops of silver nitrate, a quantity which may hence be neglected. Painfully -careful 

 testing presumed, we may therefore designate a benzaldehyde as free from chlorine 

 with all certainty, when the method mentioned yields, in the combustion of about 8 or 

 10 g. of benzaldehyde, values which are below 0.005 per cent. 



In the same way as for the purpose outlined, the method may be found to be 

 quite generally suitable technically for the quantitative estimation of the halogen contents 

 of organic halogen compounds. That would be an advantage over the method of Carius 

 since our determination is more convenient and takes less time. With easily-combustible 

 materials there will be no trouble in the combustion. Solid bodies and substances 

 which are not easily combustible would have to be mixed with alcohol or some similar 

 material. We intend to pursue these experiments. 



Borneol. — According to an English journal 1 ) ordinary camphor may be replaced 

 by Ngai camphor with advantage, especially for industrial purposes. So far the expensive 

 Ngai camphor, which comes from a weed growing abundantly in Assam and Burma 

 and which consists almost entirely of pure Z-borneol, had only been used in China 

 for the manufacture of scented Chinese inks 2 ). The high price, which had to be paid 



*) Chemist and Druggist 92 (1920), 910. — 2 ) Cf. Report 1920, 67. 



4 



