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SELECTED ARTICLES. 
ART. XXXVI.— REMARKS ON A METHOD PROPOSED BY 
DR. THOMSON, FOR DETERMINING THE PROPORTIONS 
OF POTASSA AND SODA IN A MIXTURE OF THE TWO 
ALKALIES, WITH THE APPLICATION OF A SIMILAR IN- 
VESTIGATION TO A DIFFERENT METHOD OF ANALYSIS. 
By A. D. Bache, Professor of Natural Philosophy and Chemistry, 
University of Pennsylvania. 
In a recent number* of the " Records of General Science," 
Doctor Thomson gives the following method of determining 
the proportions of potassa and soda in a mixture of the two 
alkalies. The method is accompanied by an example of its 
use. 
" 1. Convert the mixture of potash and soda into sulphates, 
render these sulphates anhydrous by ignition in a platinum 
crucible, and determine their weight. Let it amount to 29 
grains. 
" 2. Dissolve the two sulphates in water, and throw down 
the sulphuric acid by chloride of barium. Wash the sulphate 
of barytes obtained, dry it and weigh it after ignition. Let 
the weight be 43.5 grains, indicating 15t grains of sulphuric 
acid. 
" 3. Separate any excess of barytes that may have been 
added to the liquid, by the cautious addition of dilute sulphu- 
ric acid. Filter, evaporate to dryness, and ignite. The salt 
thus obtained will consist of the mixture of potash and soda 
converted into chloride of potassium and sodium. Weigh 
this salt. Let the weight be 24.5 grains. 
" Now the atom of potash is 6, and that of soda 4: and it is 
* January, 1836. On the Method of Determining- the Proportions of 
Potash and Soda, when the two Alkalies are mixed together. By Tho- 
mas Thomson, M. D., F. R. S. L. and E., Regius Professor of Chemistry 
in the University of Glasgow. 
f The equivalents of baryta and sulphuric acid are here assumed as 76 
and 40 respectively, referring them to the hydrogen unit. 
