NOVEMBEE 20, 1908] 



SCIENCE 



735 



A VACUUM STOPCOCK 



During the winter of 1908 work was under- 

 taken on the gas production of Bacillus coli 

 in synthetic culture media. The method of 

 work consisted of growing the organism in 

 high vacuum. In the course of this work 

 considerable difficulty was experienced in 

 maintaining absolutely tight stopcocks and as 

 a result a stopcock was devised that appears 

 to satisfy the conditions for a gas-tight stop- 

 cock. 



The ordinary stopcocks had to be reground 

 with jeweler's rouge, and while this precaution 

 rendered the stopcock gas-tight under con- 

 stant temperature conditions, it was found 

 that the changes in temperature from room 

 to incubator caused the two ground surfaces, 

 assisted by the resilience of the lubricant, to 

 separate and thus make the stopcock leak. To 

 overcome these difficulties the stopcock had to 

 be tied into place and mercury placed in the 

 exposed lead. 



The stopcock devised to overcome these dif- 

 ficulties is explained by the two diagrams. 

 The passage from X to F leads through an 

 obliquely drilled plug as in the ordinary im- 

 proved vacuum stopcock. At 4 a small bulb 

 takes the place of the ordinary open end. 

 Into the center of the plug, and in the same 

 plane as the oblique drilling, a drilling is 

 made as far as the level of the lead X. From 



from X to F and then it may be opened and 

 closed at will without the small bulb A ever 

 coming into communication with the passage. 

 In the above arrangement the atmosphere 

 is exerting its pressure to hold the plug in 

 place, thus overcoming the resilience of the 



Fig. 1 

 this point it continues at a right angle as 

 indicated in the diagram. The operation of 

 the stopcock is as follows. The stopcock be- 

 ing in the position indicated in Fig. 1, the 

 plug is turned through 180°, thus bringing it 

 into the position indicated in Fig. 2. The 

 stopcock is then connected with the pump and 

 the small bulb exhausted. Turning the plug 

 through another 180° will open the passage 



Fig. 2 



lubricant and pressing the two ground sur- 

 faces together constantly, in spite of the tem- 

 perature changes that tend to let one sur- 

 face expand away from the other. The lubri- 

 cant is composed of gutta-percha, hard paraffin 

 wax and a heavy mineral oil; and answers 

 admirably. Many similar lubricants are de- 

 scribed in the literature. 



The above stopcocks were very neatly con- 

 structed by Eimer and Amend. 



Brown University Frederick G. Keyes 



SOCIETIES AND ACADEMIES 



THE AMERICAN MATHEMATICAL SOCIETY 



The one hundred and fortieth regular meeting 

 of the society was held at Columbia University 

 on Saturday, October 31. A single morning ses- 

 sion sufficed for the brief program. The president 

 of the society. Professor H. S. White, occupied the 

 chair. The attendance included twenty-one mem- 

 bers. The following new members were elected: 

 Professor J. A. Brewster, St. Angela's College; 

 Professor W. H. Butts, University of Michigan; 

 Dr. C. F. Craig, Cornell University; Professor 

 T. A. lHartin, Mt. Union College; Professor M. 

 T. Peed, Emory College; Mr. G. E. Roosevelt, New 

 York City; Mr. L. M. Saxton, College of the City 

 of New York. Four applications for membership 

 were received. The total membership of the 

 society is now 605. 



A list of nominations of officers and other 

 members of the council was adopted and ordered 

 placed on the official ballot for the annual election 

 at the December meeting. It was decided to hold 

 the annual meeting at Baltimore, on Wednesday 

 and Thursday, December 30-31, in affiliation with 



