EXPERIMENT STATION BULLETINS. 



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gear "j", which was run by a small motor not shown in the figure. It 

 was thus possible to start and stop the pumps (which were duplicates) 

 at the same time and to run them at the same speed. There was not 

 found, on the market, a small pump in which the gas to be circulated 

 did not come in contact with the boxing of the pulley-journal of the 



Fig. 1. Apparatus used in determining the influence of gasoline and carbon disulphide 

 upon the absorption activity for oxygen of insect tissue-extract plus hydroquinone solution. 

 (Duplicate systems) a = gas burettes; b = mercury mugs; c = gas-containers; d = potash 

 absorption flasks ; e = mercury manometers ; f = burettes for hydroquinone solution ; 

 g = circulating pumps ; h == mercury mugs ; j = reducing gear. 



pump. In these experiments, it was necessary to know that no leak or 

 gas exchange could take place at that point. The two circulating pumps 

 represented in Fig. 1 were, therefore, designed to meet the necessity. 

 Each pump was filled with mercury to a certain level as shown by line 



