PROPERTIES OF THE BACTERIOPHAGE 279 



illustrative experiment. Incidentally, it may be well to describe the 

 apparatus which I have devised for such a test for it may serve for experi- 

 ments of a wholly different nature. I believe it to be the only apparatus 

 which permits, under normal barometric pressure, or even under a higher 

 pressure, a fluid to be distilled at a low temperature with the recovery 

 of all of the volatile products and without the possibility of any loss. 

 With aqueous materials, such as a fluid culture medium, distillation 

 can be effected at 30°C. 



The apparatus (fig. 6) is composed of a conical glass receptacle pro- 

 vided with a neck having a diameter of 5 to 6 cm. and a length of 25 cm. 

 The opening is closed with a rubber stopper having a hole about 4 cm. 

 in diameter. Through this stopper a glass tube (a test-tube) with a 

 diameter of 4 cm. and a length of 40 cm. is passed. On the bottom of 

 this tube is fused a small glass hook, to which is attached by means of 

 a fine platinum wire forming a loop, a small glass bucket, 40 mm. in 

 width and 60 mm. deep, made from a test-tube.* 



The figure presented herewith shows the apparatus as assembled 

 and ready to operate. The liquid to be distilled is placed in the bottom 

 of the long-necked flask which is tightly closed with the rubber stopper, 

 and the flask is placed in a water bath at the desired temperature. The 

 flask should be immersed in the water up to withia a few centimeters 

 of the top in order to avoid a condensation of the vapor upon the walls. 

 The interior of the tube which passes through the rubber stopper is 

 cooled, either by allowing a stream of cold water to flow through it, or by 

 filling the tube with cracked ice which may be renewed from time to 

 time, or by filling it with a refrigerating mixture of cracked ice and salt. 

 The liquid in the bottom of the flask evaporates, the vapor condenses 

 on the outer surface of the refrigerating tube, and the drops find their 

 way to the bucket suspended below. When the cooling is effected by 

 a stream of water cooled to 15°C. distillation can be satisfactorily 

 effected at a temperature of 43 to 45°C., with cracked ice, at about 

 35°C., and with a mixture of ice and salt, at about 30°C. 



Twelve tests on the behavior of the bacteriophage during distillation 

 have been carried out with this apparatus, each time evaporating 30 

 cc. of bacteriophage filtrate to dryness, at temperatures varying between 

 35 and 48°C. Uniformly these tests have failed to show bacteriophage 



* Obviously these dimensions may be varied in accordance with the use to be 

 made of the apparatus. If it is desired to distill some cubic centimeters of a 

 fluid the apparatus can be made with an Erlenmeyer flask with thick walls, or of a 

 Kitasato flask, with the lateral arm closed. 



