£08 Dr Fyfe’s A nalysis of Sulphate of Nickel and Copper. 
produces undulations of different density, by which the sono- 
rous undulations are divided and interrupted, in the same man- 
ner as light is in passing through alcohol and water imperfectly 
mixed, or any medium of heterogeneous density. Now, at Win- 
ter Harbour, the temperature of the ground and that of the air 
near it had a wonderful degree of uniformity. The absence of 
the sun prevented any difference of density arising from the une- 
qual heating of the ground ; and consequently, the mass of air, 
above a mile long, which, on the 11th February, intervened 
between Captain Parry and the sailor whose song he heard 
through that interval, was perfectly homogeneous, and offered 
no obstruction to the undulations which the voice of the sailor 
had propagated through it. In proof of this opinion, we have 
only to look at the temperature for that day, and we shall find, 
that the maximum and minimum temperatures were — 38° and 
— 42°, and the mean 89°.77 ; the whole range of temperature 
for that day being only 4° ! which is a satisfactory proof of the 
perfect homogeneity of the strata of air incumbent on the 
ground* 
Art. XXX. — Analysis of Sulphate of Nickel and Copper. 
By Andrew Fyfe, M. D., Lecturer on Chemistry, Edin- 
burgh. Communicated by the Author* 
1 HE salt, which is the subject of the following paper, was 
given to me for analysis, by Dr Brewster, in consequence of 
his having found it to possess only One axis of double refrac- 
tion, contrary to the general law which he had established, that 
all sulphates with a single base (and among these certain crys- 
tals of sulphate of nickel) have Two axes of double refraction*. 
The salt was entirely soluble in water, forming a green solu- 
tion. When nitrate of baryta was added to the solution,’ a 
white precipitate fell, which was insoluble in nitric acid. Am- 
monia threw down a greenish powder, soluble in excess of the 
alkali, and the fluid acquired a blue colour. On the addition 
of prussiate of potassa, a precipitate, partly of a greenish, part- 
* See this Number, p. 6, 
