PROTIUM DEUTERIUM TRITIUM TAYLOR 125 



tremendous improvements would be possible in such industrial opera- 

 tions, under much simpler working conditions. Deuterium points 

 the direction which research in technical catalysis must take. 



Biologically, heavy water has proved to be of the utmost interest. 

 Seeds of the tobacco plant do not germinate in heavy water. Fresh- 

 water organisms such as tadpoles and guppies die quickly when placed 

 in heavy water. Unicellular organisms, such as paramoecium or 

 euglena, are more resistant, but are eventually killed. The lumines- 

 cence of bacteria is modified in heavy water media, and the rate of 

 respiration markedly reduced. Yeast ferments sugar in heavy water 

 at only one ninth the rate in ordinary water. The enzyme catalase 

 present in the blood stream and whose function it is to detroy hydro- 

 gen peroxide does so at only one-half the normal rate in 85 per cent 

 heavy water. The action of the heavy water may be likened to that 

 of a generally unfavorable environment leading to progressive 

 changes in the cell. It would seem that the changes observed are the 

 result of differential effects on the rate of biochemical reactions, ex- 

 amples of which have just been given in respect to enzyme reactions. 

 The use of heavy water as an indicator of reaction mechanism in 

 biological systems is evident from reports of recent English work in 

 which it has been shown, by experiments conducted in heavy water, 

 with organisms such as B. coli and B. aceti, that the present accepted 

 mechanisms for their activity need to be modified in the light of re- 

 sults obtained with media containing deuterium instead of hydrogen. 



The known compounds containing hydrogen are numbered in the 

 hundreds of thousands. It is evident that an overwhelming program 

 of research replacing hydrogen by deuterium is possible. Judiciously 

 conducted, such a program will aim at the preparation of materials 

 with which problems in physicochemical science may be tested. There 

 are already the beginnings of such a program to be recorded. A 

 number of exchange reactions between heavy water and different 

 substances have thrown light on the problems of mechanism involved. 

 Thus, ammonia gas, NH3, exchanges very rapidly with heavy water, 

 D2O, to give ammonia in which the hydrogen atoms are replaced by 

 deuterium atoms to an extent depending on relative concentrations. 

 In cane sugar, however, only about half the hydrogen atoms are 

 readily replaced and these atoms are those present in the molecules 

 as hydroxyl (OH) groups. Acetylene, C2H2, and acetone CH3 

 COCH3, do not replace their hydrogens for deuterium in acid solu- 

 tions or in plain heavy water but do so more or less readily in basic 

 solutions. The former exchange indicates definitely the acidic nature 

 of acetylene. The latter demonstrates that acetone in basic solutions 

 exists partially in another form CHg* COH: CH2, which is acidic in 

 nature due to the H attached to oxygen. In acetic acid CH3COOH 

 only the final acidic H is readily replaceable by D. In a compound 



