THE BAUME HYDROMETERS. 



JtEAD AT TUE PHILADELPHIA MEETIKd. 1881. 



By v.. V. Chandleu. 



In 1768, Autoine Bauiiie, a cUemist in Paris, published an account of two new instruments 

 which he had devised for determining the specific gravity of liquids. 



These instruments met with speedj' acceptance on the part of practical men, and are now more 

 extensively used in manufacturing establishments than any others. 



Acids, alkalies, sugar solutions, petroleum oils, &c., are almost exclusively described in 

 degrees Baum^. 



The degrees on the Baume scale are entirely arbitrary, and bear no obvious relation to the 

 specific gravity of the liquid. 



Baum^'s hydrometers are instruments of even divisions. The special recommendation which 

 has led to their extensive use among practical men is the simplicity of the numbers representing 

 the specific gravity of the liquid. For liquids heavier than water the entire range is from zero to 

 about 70 degrees. For liquids lighter than water, 10 to 80. 



The numbers, therefore, are very easy to remember, and far more convenient on that account 

 than the number expressing the true specific gravity, which for a liquid heavier than water would 

 be 1 and a decimal of three figures usually, as for example 1.237. 



Although Baum6 described with great accuracy the method which he employed for securing 

 the scale for his hydrometers, and it would seem, therefore, as though no difficulty existed to pre- 

 vent the reproduction of his instruments, nevertheless it is a fact that among instrument-makers 

 the scale has been so far modified from time to time that we have the greatest variety of instru- 

 ments purporting to be Baume's, each one of which has a set of degrees of an entirely difiereut 

 value from that exhibited by any other. 



I have found twenty-three different scales, published by as many different writers, for liquids 

 heavier than water, the highest of which gives as the value of 66° Baume 1.8922; the lowest 1.730, 

 no one of which can be said to be correct, or to have been obtained by following Baume's directions. 



For liquids lighter than water I have found eleven scales in which the value of 47° Baume 

 varies from 0.7978 to 0.7909. 



Baume's directions for the construction of his instruments are very simple, and it is almost 

 incredible that such deviations should have occurred in connection with the instruments. 



It has often been suggested that .the only safe plan is to abandon the use of them entirely, 

 and rely upon instruments which record at once the true specific gravity, referred to that of water 

 as a unit. 



The answer to this is that practical men will not abandon them, having become wedded to 

 them, and preferring them on account of the simplicity of the numbers involved, and it would be 

 impossible to induce them to give them up. 



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