364 REPORT—1905. 
3. The Role of Enzymes in Plant Economy. 
By Dr. EK, FRANKLAND ARMSTRONG. 
In studying the synthesis of disaccharides, both by means of acids and by 
means of enzymes, attention must be directed to the following points :— 
1. That acid and enzyme action are fundamentally similar. 
2, That the distinction between them arises from the latter acting selectively, 
in consequence of their power of associating themselves with the hydrolyte. 
3. That the condition of the carbohydrate in solution is of primary impertance,, 
but that this condition may to some extent be determined by the enzyme. 
THURSDAY, AUGUST 17. 
The following Papers and Reports were read :— 
1. The Propagation of Explosions in Gases. 
Ly Professor H. B. Dixon, 7.2.8. 
The author gave a history of the researches on the propagation of explosions in 
gases, and discussed Berthelot’s theory and his own ‘sound-wave’ theory on the. 
mode of propagation. Photographs of the explosion-wave were shown, and the. 
author explained how he had followed photographically the flame from its initia~ 
tion until the setting up of the ‘detonation,’ and pointed out the influence of the, 
position of the spark and the length of the column of exploding gases. 
Experiments (now being carried out) on the specific heat of gases at high 
temperatures, showing how the velocity of sound might be determined in a heated, 
gas, were also described. 
2. Lhe Influence of Phase Changes on the Tenacity of Ductile Metals at the: 
Ordinary Temperature and at the Boiling-point of Liquid Air. By 
G. T. Bemtey and H. N. Brmpy, B.Sc. 
The observations recorded in this paper are intended to prepare the way for: 
a more direct attack on the problems of molecular cohesion, by the establishment. 
of clearer views as to the influence of changes of phase on the tenacity of ductile. 
metals at various temperatures, 
According to the phase theory of the hard and soft states in metals which was. 
first developed by one of the authors more than a year ago, the changes of state from 
hard to soft and from soft to hard were shown to be due to the changes of phase. 
brought about, in the one case by heat, and in the other by mechanical deforma- 
tion or flow. In the ductile metals the crystalline is the mechanically unstable. 
phase, while the amorphous only becomes thermally unstable when a definite. 
temperature is reached, , 
The comparative mechanical instability of the two phases is well illustrated 
in the stretching of wires under tension. Annealed wires, which are in the C 
phase, stretch when they are stressed beyond the yield point; hardened wires, 
which are partly in the A phase, do not stretch—they break without extension 
when their limit of tenacity is reached. 
The homogeneous C phase in ductile metals has no true breaking-point— it 
yields and stretches when stressed beyond the elastic limit, and in so doing it 
passes partly into the A phase, and rupture occurs at the breaking-point of the 
mived structure. The tenacity of the mixed structure approaches, but never 
quite reaches, that of the homogeneous A phase. For the purpose in yiew it 
was necessary to obtain the metals as nearly as possible in this homogeneous 
condition, 
Wire drawing was the means employed for the breaking down of the C phase. 
After a wire has been stretched to four or five times its original length by 
