306 SECTIONAL TRANSACTIONS.—B. 
8. Prof. E. C. C. Baty, F.R.S., Mr. F. M. Jonnson, Mr. H. G. Lirrier, 
and Miss Epira Morrison.—further Investigations on the 
Photosynthesis of Naturally Occurring Compounds. 
The earlier results obtained by Baly, Heilbron, and Barker, on the conversion of 
carbonic acid into formaldehyde by the action of light, have been adversely criticised. 
It has now been found that the discrepancies are due to the existence of a photo- 
stationary state. In the original paper the view was put forward that the synthesis 
of carbohydrates takes place in two stages, the first being the production of formal- 
dehyde, which under suitable conditions polymerises into reducing sugars. This view 
is not correct, since under the action of light the carbonic acid is converted into 
active formaldehyde which at once polymerises into carbohydrates. 
In the complete absence of impurities, a photostationary state is set up which can 
be represented by the equation 
6H,CO,===C,H,,0,+60, 
The removal of the oxygen causes the reaction to proceed from left to right. In the 
living plant the oxygen is removed from the sphere of action by the plant pigments. 
Investigation has also been made of the compounds formed by the polymerisation of the 
active formaldehyde, and it has been found that the first products are hexose sugars. 
The phenomenon of the photostationary state seems also to exist in the photo- 
synthesis of nitrogen compounds with activated formaldehyde, reactions in which 
again oxygen is evolved. Thisis of some importance, because the removal of the oxygen 
is necessary for the photosynthesis to proceed. 
The very remarkable influence of the hydrogen ion concentration in the photo- 
synthetic process has been demonstrated, and it appears that this is one of the most 
important factors. 
9. Prof. JosepH Remziy and Mr. Denis Mappen.—Velocity of 
Decomposition of Heterocyclic Diazonium Salts. 
The diazonium salts from heterocyclic amines generally show a close resemblance 
to similar substances from aromatic amines. Many of the heterocyclic diazonium salts, 
however, even in ring compounds of a simple nature (e.g. 4 amino 3.5-dimethyl- 
hydrazole—Morgan and Reilly, J.C.S., 1914, 105, 436), show a remarkable stability, in 
marked contrast with corresponding benzenoid substances. 
In our investigations the titration method of Hirsch (Ber., 1891, 24, 324) has not 
been found satisfactory, ‘The method of Hausser and Muller (Bull. Soc. Chim., 1892 
(IIL) 7, 721) was also unsatisfactory, and our first effort was to improve it. Our process 
consists in heating in a thermostat a solution of the diazonium salt contained in a 
quartz tube, through which a current of air-free carbon dioxide (prepared by. Farmer’s 
method, J.C.S., 1920, 117, 1446) is passing and collecting the nitrogen evolved over 
caustic potash. Owing to the high temperature employed, a condenser was interposed 
between the tube containing the solution and the water-jacketed azotometer. By the 
use of the stream of inert gas, it is possible to overcome the difficulties met with by earlier 
investigators. Thus, by means of a control experiment, the time necessary for the 
solution to acquire the temperature of the thermostat was determined. A thorough 
sweeping with carbon dioxide expels the nitrogen formed during this time, so that 
the true starting-point can be determined. 
In the first instance, the comparative stability of 4 amino, 1-Phenyl, 2-3 dimethy]l- 
pyrazolone, 4 amino, 3-5 dimethylpyrazole and 4 aminopyrazole was determined, 
and the investigation is being extended to other heterocyclic amines and to include 
the influence of catalysts on the reaction. . 
As an example of the stability of these compounds under the conditions of the 
experiment, the following figures for the diazonium chloride from 4 amino, 1-Pheny]l, 
3-5 dimethylpyrazolone are given. After five hours heating at 100° C., approximately 
45 per cent. of the possible amount of ‘ diazo’ nitrogen is evolved ; after ten hours, 
approximately 60 per cent.,and after twenty hours, less than 90 per cent. At this stage 
