REPORT
culating machines, and at least one balance maker is noted for outstanding service and prompt attention to customer service problems. SUMMARY
the ONLY balance for controlled environmental testing ...under vacuum or pressure AV ANALYTICAL
RV SEMI-MICRO
FV MICRO
200 gr.
100 gr.
10 gr.
1 mg./div.
0.1 mg./div.
0.01 mg./div.
Readability by estimation
0.1 mg.
0.01 mg.
0.001 mg.
Reproducibility
± 0 . 1 mg.
±0.03 mg.
±0.003 mg.
Capacity Sensitivity
The name Ainsworth is your guarantee
WM. AINSWORTH & SONS, INC. A BALANCE FOR EVERY NEED
2151 LAWRENCE STREET · DENVER, COLORADO 80205 Telephone Area Code 303 255-1723 Circle No. 25 on Readers' Service Card
46 A
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ANALYTICAL CHEMISTRY
The acquisition of one of these instruments represents the expenditure of a large sum of money, and as in purchasing any major instrument, adequate justification will have to be demonstrated. I t is impossible to offer advice on a particular instrument; first, the successful operation of these elemental analyzers will depend to a large degree on the skill of the user and the conditions under which it will be used. Purchasing an instrument does not automatically imply that one is buying skill and experience along with it. At least one of the suppliers intimates that he does not wish to have his instrument in the hands of persons that are not already competent in the art. Second, the usual microchemical balance discipline must be maintained ; in some cases this will require even more than usual care. For example, weighing of the absorption tubes used in the Coleman Analyzer presents a real challenge because they contain no capillary constrictions to prevent diffusion while weighing. Third, discrimination in sample preparation and evaluation of results will still have to be exercised; no procedure or instrument is capable of producing valid results when analyzing an impure sample. And last, these instruments have no history of performance to aid their evaluation. Each has been designed by workers of exceptionally high technical ability, and in their hands, these instruments have performed satisfactorily. Prices of these instruments range from about $2,500 to $12,500, and with the exception of the F & M instrument, do not include the price of the balance. One added advantage of the Technicon instrument is that the sample used is in the microgram range, a maximum weight of about one milligram being advised. This sample size may be unpopular to workers accustomed and equipped for work in the milligram range, but just as
