PROCEEDINGS OF THE MEETING. XIX 



mistry, besides the great subject of isomorphism to which I 

 have referred, there are some other yet undecided questions, 

 as for instance those concerning the existence and relations 

 of the sulpho-salts and chloro-salts ; and these are not small 

 points, for they affect the whole aspect of chemical theory, and 

 thus show us how erroneously we should judge, if we were to 

 consider this science as otherwise than in its infancy. 



" In every science, Notation and Nomenclature are questions 

 subordinate to calculation and theory. The Notation of Cry- 

 stallography is such as to answer the purposes of calculation, 

 whether we take that of Mohs, Weiss, or Nauman. It appears 

 very desirable that the Notation of Chemistry also should be so 

 constructed as to answer the same purpose. Dr. Turner in the 

 last edition of his Chemistry, and Mr. Johnston in his Report, 

 have used a notation which has this advantage, which that 

 commonly employed by the continental Chemists does not 

 possess. 



" I have elsewhere stated to the Association how little hope 

 there appears at present to be of purifying and systematizing 

 our mineralogical nomenclature. The changes of theory in 

 Chemistry to which I have already referred, must necessarily 

 superinduce a change of its nomenclature, in the same manner 

 in which the existing nomenclature was introduced by the pre- 

 valent theory ; and the new views have in fact been connected 

 with such a change by those who have propounded them. It 

 will be for the Chemical Section of the Association to consider 

 how far these questions of Nomenclature and Notation can be 

 discussed with advantage at the present Meeting. 



" The Reports presented at the last Meeting had a reference, 

 for the most part, to physical rather than physiological science. 

 The latter department of human knowledge will be more pro- 

 minently the subject of some of the Reports which are to come 

 before us on the present occasion. There is, however, one of 



two axes of double refraction ; and which was afterwards found to confirm the 

 law, the apparently rhombohedral forms being found by Mr. Haidinger to be 

 not simple but compound. It seems, however, that the solution of the difficulty 

 (for no one now will doubt that it has a solution,) is somewhat different. There 

 appear to have been included under this name two different kinds of crystals 

 belonging to different systems of crystallization. Some which Mr. Brooke found 

 to be rhombohedral, Sir David Brewster found to have a single optical axis 

 with no trace of composition ; others were prismatic with two axes ; and thus 

 Mr. Brooke's original determinations were probably correct. The high reputa- 

 tion of the parties in this controversy does not need this explanation ; but pro- 

 bably those who look with pleasure at the manner in which the apparent excep- 

 tions to laws of nature gradually disappear, may not think a moment or two lost 

 in placing the matter on its proper footing. 



