SCIENCE- ADYEBT1SEMENT8 



HIGH VACUUM PUMPS 



W henever in lecture-room or laboratory practice, really high 

 \atuum IS required, we recommend the Condensation Pump devel- 

 oped by Dr. Irving Langmuir of the General Electric Company — believ- 

 iiig it to be superior to any other as yet obtainable. 



The Langmuir Pump operates with surprising rapidity, and there 

 SLems to be no practical limit to the degree of exhaustion that can be 

 pioduccd 



Some form of auxiliary pump must be used; and for that purpose 

 we offer a special G.E. two-stage oil-sealed mechanical pump, which 

 is capable of producing a vacuum of 

 o.ooi mm. when used alone. 



The picture shows a complete out- 

 fit comprising Langmuir Condensation 

 Pump, two-stage auxiliary pump and 

 % H.P. motor — all mounted together on 

 one base. 



Write for descriptive bulletin S-965 



JAMES G. BIDDLE 



1211-13 Arch St.. Philadelphia 



GAS MACHINES 



Supply the highest quahty 

 gas for factories, colleges, pri- 

 vate houses, villages, labora- 

 tories, hospitals, etc. 



Cheapest and most reliable 

 gas service available. 

 Write for complete description 



Sole agents 



PAL2 COMPANY 



APPARATUS FOR INDUSTRIAL AND LABORATORY USE 

 153 West 23rd Street, New York, N. Y. 



