248 Biographical Memoii- of the late Dr Turner. 



Every one familiar with chemical analysis and its applications 

 to the atomic theory must be aware, that the exact constitution 

 of the chloride of barium is one of the most essential facts in this 

 branch of chemistry, because by its means, and from its compo- 

 sition, are deduced the combining proportions of a very great 

 number of important compound bodies. Its constitution forms, 

 in particular, a material element of the researches detailed by 

 Dr T. Thomson in 1825, in his great work on The First Prin- 

 ciples of Chemistry. Unhappily, the correctness of Dr Thom- 

 son's experiments on the subject was called in question by Ber- 

 zelius, the first authority, pei'haps, in analytic chemistry ; and, 

 still more unhappily, the discussion was conducted by that phi- 

 losopher with a spirit of acrimony, not less at variance with the 

 great cause of truth than it was unworthy of his own high char- 

 acter, and of the sober dignity of the science he cultivated. It 

 was no feeble proof of Dr Turner's consciousness of his own 

 powers, and of his reliance in the faith reposed by the public 

 equally in his accuracy of research, and in his rectitude of pur- 

 pose, that he ventured to step forth as arbiter between such men, 

 and in such a cause. He did, however, venture ; and he de- 

 cided the question not merely to the satisfaction of the chemical 

 world, but likewise with such kindhness of disposition and urba- 

 nity of manner, as to have lost, in consequence, neither the re- 

 spect of the one rival, nor the friendship of the other. His paper, 

 considered upon its own intrinsic merits, furnishes a memorable 

 example of exact analytic investigation. He had to determine 

 the true constitution of chloride of silver, and the quantity, both 

 of sulphate of baryta and of chloride of silver, thrown down in a 

 solution of chloride of barium respectively by nitrate of silver 

 and by sulphuric acid. The last of these points he determined 

 by a series of experiments, the results of which differed from one 

 another by no more than 3 in the second decimal figure. In 

 both of the others, the differences in each set of experiments were 

 2 only in that figure. 



This investigation was the first of a projected series on simi- 

 lar subjects ; and it was followed up in 1833 in a paper of great 

 experimental research, where he has determined the atomic 

 weights of chlorine, nitrogen, and sulphur, lead, silver and mer- 

 cury, as well as the composition of several of their compounds.* 



* Philosophical Transactions cxxiv 523. 1833. 



