Foundations of the atomic theory : comprising papers and extracts by John Dalton, William Hyde Wollaston, M. D., and Thomas Thomson, M. D. (1802-1808).

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Foundations of the atomic theory : comprising papers and extracts by John Dalton, William Hyde Wollaston, M. D., and Thomas Thomson, M. D. (1802-1808). Source: Wellcome Collection.

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    both in number and weight; the principle will be entered into more particularly hereafter, as far as respects the individual results. It is not to be understood that all those articles marked as simple sub- stances, are necessarily such by the theory ; they are only necessarily of such weights. Soda and potash, such as they are found in com- bination with acids, are 28 and 42 respectively in weight; but according to Mr Davy’s very important discoveries, they are metallic oxides ; the former then must be considered as composed of an atom of metal, 21, and one of oxygen, 7 ; and the latter, of an atom of metal, 35, and one of oxygen, 7. Or, soda contains 75 per cent, metaland 25 oxygen ; potash, 83.3 metal and 16.7 oxygen. It is particularly remarkable, that according to the above-mentioned gentleman’s essay on the Decomposition and Composition of the fixed alkalies, in the Philosophical Transactions (a copy of which essay he has just favoured me with) it appears that “ the largest quantity of oxygen indicated by these experiments was for potash 17, and for soda, 26 parts in 100, and the smallest 13 and 19.” ON SUPER-ACID AND SUB-ACID SALTS. By WILLIAM HYDE WOLLASTON, M.D., Sec. R.S.* ReadJan. 28, 1808. IN the paper which has j-ust been read to the Society, Dr Thomson has remarked, that oxalic acid unites to strontian as well as to potash in two different propor- tions, and that the quantity of acid combined with each of these bases in their super oxalates, is just double of that which is saturated by the same quantity of base in their neutral compounds.! As I had observed the same law to prevail in various other instances of super-acid and sub-acid salts, I thought * From the Philosophical Transactions, vol. 98 (for 1808), pp. 96-102. + [See the extracts from Dr Thomson’s paper on Oxalic Acid, on page 41.]