BY R. GREIG-SMITH. 



539 



The loss of paraffin is approximately 5 %. The melting points 

 of the recovered paraffin from the control and 10 days' tests were 

 determined, and both were found to be the same, viz., 45°. 



Powdered casein, the granules of which passed through a No. 30 

 sieve, was used in the next experiment. About ten grams of 

 paraffin were added to 130 grams of casein, and the mixture was 

 heated at 100° and stirred until it was considered that the hydro- 

 carbon had been evenly distributed. It was then cooled, powdered, 

 and sifted. Fifteen-gram portions were weighed out, placed in 

 beakers, mixed with four grams of kieselguhr, and moistened 

 with 20 c.c. of water containing a suspension of Bac. prodigiosus. 



The loss of paraffin ranges from 11 % to 22 %. 



During the direct estimation of the total paraffin, several 

 observations showed that the method of recovery was capable of 

 improvement. When the cultures were spread out to dry, pre- 

 vious to the ethereal extraction, a strong odour of ammonia was 

 given off, and this was followed by a pungent gas, sometimes 

 resembling formaldehyde, at others acrolein. This led to the 17 

 and 24 days' tests being mixed with sodium carbonate and 

 powdered lime, respectively, before drying. But even this did 

 not prevent the presence of volatile acids in the recovered 

 paraffin. A trace of lecithin was also present. A method was 

 accordingly employed in the later experiments that eliminated 

 these objectionable substances. 



The method simply consists in digesting the paraffin recovered 

 by the Soxhlet apparatus, with 5 c.c. of 10% sodium hydrate, 

 transferring to a 50 c.c. graduated Wehrner-Schmit tube, allow 



