— 123 — 



next a third line appears gradually between the two, and becomes 

 more and more pronounced, so that at a given moment of the reaction 

 three absorption lines of equal intensity can be observed. Subsequently 

 the line fi appears to become displaced towards the right; soon 

 afterwards a has entirely disappeared. There remain finally two 

 absorption lines, a very distinct one on the left, and a diffuse one on 

 the right. The appearances are somewhat different if the blood solution 

 is previously reduced by polysulphides of ammonium. In such case 

 only the one line of the reduced haemoglobin is visible, which grad- 

 ually becomes denser, and forms then the above-mentioned left line, 

 whilst the diffuse line is formed on the right; this is the characteristic 

 spectrum of haemochromogene; the centre of the intense line is at 

 X 560, that of the other diffuse and broader line at X 520. The position 

 of the absorption lines is always the same, whatever aldehyde is 

 used, but their width and intensity depend upon the quantity of the 

 aldehyde added. 



If under the last-mentioned conditions a ketone is employed 

 instead of an aldehyde, only the reduced haemoglobin absorption 

 spectrum will be observed. The spectrum of the aldehyde compounds 

 follows that of haemochromogene. Of aldehydes which contain, besides 

 the aldehyde - group , also other reactive groups, some are without 

 action on haemoglobin, whilst others give the above reaction. 



The reaction of aldehydes on haemoglobin is very reliable and 

 sensitive. For example, in order to produce the reaction with 2,5 cc. 

 reacting blood 1 ), 0,00039 gram citral are sufficient. Equal quantities 

 of an aldehyde act in the same length of time always with equal 

 intensity; on the other hand, the intensity and the commencement of 

 the reaction are always proportionate to the reacting quantities of 

 aldehyde. Bruylants has often found these conditions confirmed during 

 the action of citral on haemoglobin, and has in consequence worked 

 out on this basis a method for the quantitative determination of citral 

 in lemon oil, which is said to give satisfactory results. We will return 

 to this method when the further publications promised by Bruylants 

 have come to hand. 



Physical notes. 



Some years ago Ciamician and Silber showed that acetone 

 in aqueous solution is split up hydrolytically, by the action of light, 

 into acetic acid and methane: — 



CH3.CO.CH3-> CH3.COOH + CH 4 . 



*) This is obtained by adding to 19 cc. of a 3,7 per cent, solution of defibrinated 

 pig's blood 1 cc. ammonium sulphide. 



