THE ENERGY OF THE LIVING PROTOPLASM. 171 
If we add, for example, to the mixture mentioned, sodium 
carbonate, or boil the mixture with addition of calcium car¬ 
bonate, no trace of the rancid smell will be noticed after addition 
of a mineral acid ; the absorbed oxygen is here too quickly used 
up for oxidation. 
Another process, hitherto unexplained, is the easy reduction 
of nitrates to ammonia in the formation of proteids (cf. Chap. V). 
As there exists no nascent hydrogen in the living cells, I had 
long entertained the view that glucose under the katalytic 
influence of the living protoplasm would be the reducing agent, 
and recently have succeeded in imitating this reduction by 
means of platinum-black. I heated in my first experiment a 
solution of 3 g. potassium nitrate and 10 g. glucose, in 300 g. 
water with no g. platinum-black for 6 hours to 60-70° and found 
that 45.6 % of the nitrogen of the nitrate had been converted 
into ammonia. This reduction can even succeed at the 
ordinary temperature. If 50 cc. of a mixture of a 5-10 % glucose 
solution with 1-2 % calcium nitrate and 10 g. platinum-black is 
left to stand for 4-5 days in a closed flask, we observe upon 
supersaturation with caustic lye a strong ammoniacal odour, while 
in a control experiment without the platinum no trace is obser¬ 
vable. 1 (2) If we modify the experiment by increasing the amount 
of the nitrate to three times that of the sugar, we find on heating 
that the acid reaction generated at first soon diminishes and 
finally gives way to an alkaline one, and then the ammonia pre¬ 
viously formed becomes very perceptible by its odour.The 
platinum-black imparts to the hydrogen atoms of the glucose 
increased motions, thereby loosening the existing affinities, and 
y 
awakening others, whereby a reduction of the nitrate is caused, 
i.e ., an exchange of oxygen and hydrogen between the nitrate and 
the sugar. 
In a similar way, chlorates are reduced to chlorides ; 
sulphates however resist its action and require evidently more 
(1) Other control experiments were also made, which proved beyond any doubt 
that only the platinum-black itself and not any oxidation product or bacterial action 
was the cause of the formation of ammonia. 
(2) If the mixture is rendered alkaline before the platinum-black is added, no 
ammonia will be produced, a result which finds its explanation in what has been 
mentioned above. 
