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only is chloride of ammonium vapour given off for a long 
while with the double salt, at a temperature much above that 
at which chloride of ammonium alone volatilizes, but when 
that salt is completely expelled, the chloride of magnesium 
remaining is perpetually being decomposed with evolution of 
free chlorine, and, frequently, the formation of a crystalline 
crust of periclase lining the crucible. Platinum thus purified 
is softer and whiter than ordinary commercial platinum. 
The method is not available solely for the removal of iron, 
but retrieves crucibles that have become dark coloured and 
brittle from exposure to gas flame, as well as crucibles that 
have been attacked by silicates during fusion of these with 
carbonate of sodium, I cannot conclude this note without 
remarking on the extreme facility with which platinum 
becomes impure by heating in contact with matters containing 
only a very small proportion of substance capable of attacking 
the metal. Thus, a platinum crucible becomes sensibly 
impure after prolonged ignition at a high temperature, bedded 
in commercial magnesia. On the other hand, I have kept a 
platinum crucible at a constant weight, to the tenth of a 
milligramme, over a series of intense ignitions, when the 
precaution has been taken to bed it in chemically pure 
magnesia. 
A conversation took place on the cattle plague, in the 
course of which the President and Mr. Spence stated that 
the use of carbolic acid as a disinfectant had been quite 
successful as a preventive in the limited number of cases 
tried, none of the cattle on the farms where it had been 
regularly and properly used having yet been attacked by the 
rinderpest. People rarely used enough. 
An opinion was strongly expressed by some members that 
the means which had been adopted to arrest the progress of 
the disease had, in fact, served to propagate it and extend its 
ravages, as numerous instances could be cited in which the 
