540 NOTE ON THE DESTRUCTION OF PARAFFIN, 



ing the alkaline liquid to measure about 20 c.c, adding ether to 

 the 49 c.c. mark, and, in the casein tests, adding 1 c.c. of rectified 

 spirit. After a vigorous shaking, the ethereal layer is read off, 

 and lOc.c. portions pipetted out into flat-bottomed, metal evaporat- 

 ing dishes. The ether is allowed to evaporate at 30°, and then 

 dried for two hours in the water-oven. The procedure is similar 

 to that employed in the estimation of fat in milk by the Wehrner- 

 Schmit process. 



Fifteen grams of paraflaned casein were mixed with one gram 

 of kieselguhr and one gram of calcium carbonate, placed in two- 

 ounce bottles, and, after sterilisation in the autoclave, treated 

 with 5 c.c. of a suspension oi Bac. prodigiosus or of soil-organisms 

 (5 grams of soil to 100 c.c. of water). The bottles were incubated 

 at 28°. 



Control 



Fermented with soil-organisms, 15 days 



Fermented with Bac. prodigiosus, 25 days 



Paraffin recovered. 



•21 grams. 

 •22 „ 



The average loss for the soil-organisms is IM %, and for Bac. 

 prodigiosus 3*7 %. 



Finally, an experiment was made in which the bulky, organic, 

 nitrogenous matter was dispensed with. Kieselguhr was treated 

 with paraffin, ground and sifted. Four grams were mixed with 

 20 grams of sand and one gram of calcium carbonate, and the 

 bottles containing the mixture were sterilised in the autoclave. 

 Ten c.c. of water containing 0*1 % dipotassium phosphate, 0-05% 

 magnesium sulphate, 0-05 % sodium chloride, and either 1 % 

 peptone, 0-5 % asparagin, or 0-5 % ammonium sulphate were 

 added. The bottles were then steamed for an hour, and infected 

 with 2 c.c. of a suspension of Bac. prodigiosus, containing 12 

 million cells, or 2 c.c. of a suspension of soil-organisms (10 grams 



