130 THE ALUMNI JOURNAL 



LABORATORY NOTES. 



By Charles E. Vandekkleed. 



In answer to the query as to whether spirit prepared from concen- 

 trated nitrous ether meets the pharmacopoeial standard for strength, 

 my answer would be that it does, provided the proper precautions be 

 taken. In examination of the 80 per cent, concentrated nitrous ether 

 covering several years, I have never found a sample under strength. 

 The contents of each bottle of the concentrated ether require dilution 

 with 19 volumes of alcohol to produce a 4 per cent, spirit. The best 

 method is as follows : 



Wash the bottle of concentrated ether until perfectly clean on the 

 outside, and place it on ice or in a refrigerator. Pour 15 or 16 volumes 

 of cold alcohol into a wide-mouthed container that can be tightly stop- 

 pered. A specimen jar, or even a crock provided with a rubber casket 

 and heavy covers answers very well. Tie a cord to the neck of the 

 well-chilled bottle. Remove the stopper and plunge it, mouth upwards, 

 below the surface of the alcohol in the jar. Allow the bottle to remain 

 submerged for a few minutes, gently giving it a vertical motion with the 

 attached cord. The contents of the bottle will have become so diluted, 

 by diffusion, that the bottle may be removed and emptied into the rest 

 of the mixture without loss by evaporation. 



After securing uniformity of the mixture a portion should be re- 

 moved and subjected to the pharmacopoeial method of assay, the re- 

 mainder in the meantime being securely stoppered. Then the calculated 

 amount of alcohol to make the finished product assay 4 per cent, may 

 be added. LTnless made in very small quantities for immediate use it is 

 advisable to make the finished product to assay slightly above 4 per cent. 



A nitrometer is not absolutelv necessary in carrying out the official 

 assay process. An inverted burette which has been carefully calibrated 

 from the 50 Cc. mark to the glass stop cock will answer the purpose 

 equally well, it being necessary only to attach a small funnel by means 

 of a short piece of rubber tubing to the outlet through which the spirit 

 of nitrous ether and the reagents may be introduced. 



In the U. S. P. calculations of the ethyl nitrate strength in the assay 

 process corrections are made for temperature and for barometric pres- 

 sure, but none is made for vapor tension. \\Micn the latter correction 

 is made, the results are slightly lower, but this omission is not of much 

 consequence where only comparative results are desired. 



