REPORT FOR ANALYTICAL CHEMISTS
window polishing?
Be independent. Polish your own NaCI and KBr windows with this complete kit. Re condition fogged or scratched windows flat to less than 5 fringes of Hg green line easily, quickly. Compact outfit — 6 " χ 7" χ 11" —contains roughing, polishing and curved smoothing laps, optical flat, rouge, alcohol and sponge in a handsome wood case. All specially made for you by RIIC — the foremost firm in the accessory field. PK-01 Polishing Kit
Another top quality product from
LIMIT R E S E A R C H
C O R P O R A T I O N
Box 8 5 2 , Darien, Conn. Phone (203) 655-3991 Circle No. 155 on Readers' Service Card 32 A
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ANALYTICAL CHEMISTRY
procedures were used. One was based on measurements of the densities of various carbon-containing gases, rela tive to the density of oxygen. The re sults of the measurements were not very consistent and generally too low by 0.05 to 0.1 percent. Another pro cedure was based on determining the weight of carbon dioxide produced by the burning of selected hydrocarbons. There were two likely sources of er rors in this method—inadequate purity of the hydrocarbons and uncertainties in buoyancy corrections caused by changes in the density of the carbon dioxide absorbent. Over a compara tively short period of time, the accepted atomic weight of carbon changed from 12.00 to 12.005, then to 12.010, and finally to 12.011. It is not surprising that Renoll, Midgley, and Henne
