1452 
not take. place through hydrogen in status nascens, but that a 
coaction between the three components is required. 
These preliminary experiments were so executed that only character- 
istic differences could be expressed; this was desirable in view 
of the fact that through impurities, presence of different modi- 
fications, structure in connection with the treatment, change of the 
surface in consequence of the solution etc. the metals in themselves 
can already give differences in the velocity of solution, which might 
vitiate the conclusions to be drawn. 
Use was made of metal in the form of gauze, leaf, or wire, of 
which a roll or spiral was made, so that the surface that was in 
contact with the liquid was as much as possible the same. Three rolls 
of the same weight and surface were now placed in three Erlen- 
meyer flasks, to each of which the acid was added, and after they had 
assumed the temperature of the waterbath benzaldehyde was added 
to the one, nitrobenzene to the second, the third containing only an 
acid by the side of the metal. As soon as a perceptible action had 
been exerted on one of the three, or as soon as in one of them the 
metal was quite dissolved, the metal was taken out of them, washed 
with water, alcohol, and ether, dried and weighed. 
The original weight of the metal, the time, and the decrease are 
recorded in the following table for a number of the principal 
experiments. 
Unless expressly stated 10 c.c. of nitrobenzene or benzaldehyde 
was added to 50 ee. of acid (Cf. the table on the next page). 
It appears very clearly from the table that the influence of reduc- 
ible compounds on the velocity of solution of a metal can be very 
great, in some cases even so great that most probably there is no 
longer question of an acceleration of an existing reaction, but of a 
new one. 
Though in almost all cases nitrobenzene shows a very great 
acceleration, also a compound as benzaldehyde appears to be able 
to exert a strong positive influence (see N°. 7, 11, 12, 18, 23, 25). 
It is clear that guided by the theory of these reactions shortly 
mentioned in the beginning, the number of combinations can be 
extended, which renders it possible greatly to increase the number 
of reducers, and to define the conditions which a reducer has to 
satisfy in a definite case. 
Thus metal, a salt of hydrochloric acid, a feeble acid (acetic acid), 
and nitrobenzene may be taken instead of metal, hydrochloric 
acid, and nitrobenzene, in this way a coaction is realized in a 
system of four components. 
