674 



EEPOET 1884. 



pared, that useful results would) probably be obtained. Experiments have proved 

 this to be the case, and in the series of homologous compounds it was found that 

 for every addition of CH„ a definite increase of what is called the ' molecular 

 rotation ' is obtained ; besides this it was found that the rotation also was capable 

 of indicating differences in the constitution of organic compounds. Isosecondary 

 and tertiary bodies give different results from normal compounds. The compounds 

 containing the halogens were also referred to, and formulae given, by which 

 molecular rotation of twenty-six series of compounds could be calculated. 



4. On the present state of our Knoiuledge of Refraction Equivalents. 

 By Dr. J. H. Gladstone; F.B.S. 



The law that the refraction equivalent of a compound is the sum of the 

 refraction equivalents of its constituents, although of general, is not of universal 

 application. The departures from it indicate some important change in the mode 

 of combination of the elements, and thus the specific refraction or dispersion of 

 light by a compound body proves a valuable means of investigating its chemical 

 structure. The papers of Briihl three years ago gave a new impulse to the study 

 of this subject, and during the past twelve months several important communi- 

 cations have been made, especially by Kanonnikov of the Kasan University, by 

 Nasini of Home, and by Bleekrode of the Hague, while the author of this paper 

 has published observations that have been accumulating for some years. 



Refraction-Equivalents of the Elements. 



Element 



Aluminium . . 



Antimony . . 



Arsenic . . . 



Barium . . . 



Beryllium . . 



Bismuth . . . 

 Boron, in Borates 



Bromine . . . 



Cadmium . . 



Caesium . . . 



Calcium . . . 



Carbon . . . 

 ,, double 



linked . . . 



Cerium . . . 



Chlorine . . . 



Chromium . . 

 „ in Chro 



mates . . . 



Cobalt. . . . 



Copper . . . 



Didymium . , 



Fluorine . . . 



Gold . . . , 



Hydrogen . , 

 Iodine . . . 



Iron, bivalent . 



„ trivalent , 



Lanthanum . . 

 Lead . . . 



Lithium . . , 

 Magnesium . 



27-5 

 122 



75 

 137*2 

 9-3 

 208-2 



11 



80 



111-6 

 132 



40 



12 



138-2 

 35-5 

 52-4 



58-7 



63-4 

 145 



19 

 196-2 



1 

 127 



56 



138 



207 



7 



24 



«P=1 



7-7 

 24-5 

 15-4 



15-8 



5-1 



38-2 



about 4 



15-3 

 131 

 19-1 

 100 

 50 



61 

 19-6? 



9-9 

 154 



about22 



10-4 

 11-5 

 233 



1-6? 

 23-1 



1-3 

 24-5 

 11-6 

 19-4 

 22-9 

 24-3 



3-5 



6-7 



Element 



Manganese 



nates . 

 Mercury 

 Nickel . 

 Nitrogen 



in permanga- 



kc. 



in bases, oxides, 



Oxygen, single bonds , 

 „ double bonds , 



Palladium 



Phosphorus . . . . 

 Platinum 



Potassium 



Rhodium 



Rubidium 



Selenium ..... 

 Silicium 



,, in Silicic Acid 



Silver 



Sodium 



Strontium 



Sulphur 



„ single bonds . 



Thallium 



Tin, bivalent .... 

 „ quadrivalent . . 



Titanium 



Uranium 



Vanadium 



Zinc 



Zirconium 



<& 



55 



200 

 58-7 

 14 



16 



106 



31 

 195 



39'1 



103-4 



85-4 



78 



28 



108 

 23 

 87-5 

 32 



203-6 

 118 



48 

 237-6 

 51-3 

 65-3 

 90 





11-7 



about 25 



19-4? 



100 



41 



51 



2-8 



3-4 



21-6? 



18-3 



24-7 



7-85 



23-4? 



12-1 



301 



7-4 



about 6 



13-2 

 i 4.4 



130 

 160 

 141 



20-4 

 27-0? 

 18-6/ 

 24-6 

 19-4 

 24-S? 

 9-8 

 21-3 



