494 



Chronicles of Science. 



[July, 



general rule this was found to be the case, but the authors brought 

 forward a few exceptional instances which at present appeared to stand 

 in opposition to their statement. Dr. Gladstone particularly referred 

 to sulphurous acid, hydrated sulphuric acid, and aqueous tartaric acid, 

 as presenting anomalies which were considered worthy of more ex- 

 tended investigation, with the view of determining the nature of the 

 disturbing causes. This mode of physical research is interesting in 

 connection with the study of isomerism, and will probably lend 

 valuable aid in determining the internal constitution of bodies ; thus, 

 whilst aniline and its isomer, picoline, gave widely different results 

 under this optical treatment, it had been found by Landolt that a 

 mixture of equal equivalents of methylic alchol and acetic acid behaved 

 precisely like its theoretical conjugate, glycerin. Dr. Gladstone 

 exhibited in a tabulated form the numbers representing the specific re- 

 fractive energies of many of the elements, multiplied by their atomic 

 weights, or " refraction equivalents," as Landolt terms it, and he 

 worked several examples by way of showing the application of the 

 formula, and the mode of deducing from compound bodies the value 

 of each constituent. The table stood thus : — 



Name of element. 

 Carbon , 









Refr. 



iction equivalent 



5-1 



Hydrogen 



Oxygen 



Nitrogen 



• 







1-5 

 30 

 3-3 



Chlorine 









8-5 



Bromine 











15.7 



Iodine 











24.4 



Sulphur 

 Phosphorus 

 Tin . 











16-0 



18-6 



. 22-0 



Sodium 











. 6-0 



Mercury 











110 



With regard to the value of carbon it was shown that the number 

 observed in the case of the diamond agreed with the results deduced 

 from the examination of carbonic oxide, carbonic acid, defiant gas, 

 and a variety of liquid hydrocarbons. Hydrogen did not appear to 

 have precisely the same value in the form of gas that it had in certain 

 hydrogen compounds, and the author stated that 7 ■ 6 was the average 

 expression, from a great number of experiments, of the value of CH 2 , 

 the oft-quoted increment of carbon and hydrogen in the homologous 

 series. Nitrogen in the form of gas was 3 • 3 as above, but in combina- 

 tion its value sometimes amounted to 4 • 2. In a similar manner the 

 numbers representing oxygen and chlorine gases became subject to 

 modification when those elements were combined. 



Some novel experiments have been lately described before the 

 Chemical Society of Paris, by M. Jodin, illustrating the action of 

 light on vegetable matter. The author destroys the vitality of green 

 leaves by immersing them in alcohol, or heating them to a high tem- 

 perature in sealed tubes, and finds that after this the leaves still 

 present some signs of life. In the light they are rapidly decolorized, 



