200 Proceedings of Societies . [February, 
obtains the following result : — When the incident ray is plane 
polarised, and the plane of polarisation is either in or perpen- 
dicular to the plane of incidence, the effedl of magnetisation is 
to introduce a component into the reflected ray perpendicular to 
the original plane of polarisation, which vanishes at the grazing 
and normal incidences, and, in the case of iron, attains a maxi- 
mum at about the angle of incidence i=6 3°2o'. He does not 
obtain any change of phase by reflection in any case. Apart 
from this question of change of phase, his results conform com- 
pletely to Mr. Kerr’s experiments on the reflection of light from 
the pole of a magnet. 
Chemical Society, January 16. — Dr. J. H. Gladstone, 
F. R.S., President, in the chair. 
The first communication was made by W. H. Perkin, F.R.S., 
“ On the ACtion of Isobutyric Anhydride on the Aromatic 
Aldehyds.” The author has studied the reaction which takes 
place when isobutyric is substituted for butyric anhydride. 
The next paper was by Dr. Dupre and PI. Wilson Hake, “ On 
Two New Methods for the Estimation of Minute Quantities of 
Carbon : (i) Gravimetric ; (2) Chromometric ; and their Applica- 
tion to Water Analysis.” (1) The Gravimetric Method : — This 
method consists essentially in burning the small quantity of carbon 
in a stream of oxygen in an ordinary combustion-tube containing 
some granulated cupric oxide. The method is found to be quite 
accurate enough for determining the carbon obtained from a litre 
of a first-class potable water. The chromometric method, or, 
as the authors name it, the nephelometric method, consists 
essentially in burning the carbon, but the carbonic acid is con- 
ducted into a standard solution of basic acetate of lead, and 
estimating the turbidity produced, as compared with that pro- 
duced by the carbonic acid evolved under similar circumstances 
by a known and nearly equal quantity of carbon, the difference 
between the two being estimated by a Mills’s colorimeter. This 
method is extremely delicate, and a difference produced by 
3-iooths of a milligrm. can be clearly estimated. The authors 
suggest their use for estimating the carbon in iron and the car- 
bonic acid in air. 
Dr. Frankland read a communication “ On Stannic Ethide,” 
by E. Frankland and A. Lawrance. In endeavouring to prepare 
stannous ethide by the adlion of zinc ethyl upon dry stannous 
chloride the authors discovered that the reaction was — 
2SnCl 2 -f-4ZnEt 2 = Sn-f SnEt 4 -f qZnEtCl, 
and that by its means stannic ethide could be prepared more 
conveniently and in larger quantities than has hitherto been 
possible. 
The next paper was by R. S. Dale and C. Schorlemmer, “ On 
Aurin,” Part II. In previous researches the authors stated that 
by the action of alcoholic ammonia on aurin, rosanilin was 
