136 
of these experiments were published in the British Associa- 
tion Report for 1855. Mr. Johnson continued to experiment 
on this subject for several years, making some of the first 
experiments on the expansion of alloys by heat, their heat 
conductivity, and specific gravity, see Phil. Mag., XIV., 
1857, XVIII., 1859, etc. Shortly after he invented a machine 
for testing the hardness of alloys and metals generally, and 
made many useful experiments. 
Perhaps, however, his most important investigations were 
on the chemical changes which pig iron undergoes during 
its conversion into wrought iron. For more than one 
hundred years previously pig iron had been converted into 
wrought iron by puddling; but it was reserved for Mr. 
Johnson to explain the nature of the change, by the careful 
analyses he made of samples of the iron, taken at short 
intervals, during the process of puddling. 
These experiments are described in detail in the Phil. 
Mag., XIV., 1857. 
Mr. J ohnson was always very active in the cause of educa- 
tion. He took a deep interest both in Owens College and 
the Manchester Grammar School. To the end of his life he 
remained a careful and constant reader ; by degrees he sur- 
rounded himself with a large and valuable library and 
picture gallery. He died on the 16th of February last, at 
his residence, Kemnal Manor, Chislehurst, after a short 
illness, much regretted by all who knew him. 
Various proposals for the celebration of the Centenary of 
the Society have been carefully considered by the Council, 
but in the present state of the Society’s finances the Council 
do not feel justified in recommending for adoption any 
scheme involving certain, and probably considerable, ex- 
pense, but which would be of very doubtful utility to the 
Society. 
At the request of the Committee appointed at the last 
annual meeting, Dr. R. Angus Smith, F.R.S., has kindly 
