C m 3 
XIX, On the manufacture of the sulphate of magnesia at Monte 
della Guardia , near Genoa. By H. Holland, M. D. F. R. S. 
Read June 13, 1816. 
The following account, which I have the honour to present 
to the Royal Society, of the manufacture of sulphate of 
magnesia at Monte della Guardia, near Genoa, has been 
drawn up chiefly from the note I made, when visiting this 
spot, in the spring of 1815. These notes have received addi- 
tions from a paper, drawn up in 1803, by my friend Signore 
G. Mojon, lecturer on chemistry at the college of Genoa, 
who has bestowed much attention on the subject, and made 
several experiments on the composition and comparative 
purity of the manufactured salt.* 
The Monte della Guardia, situated eight miles to the N. 
west of the city of Genoa, is one of the higher points in that 
part of the chain of the Ligurian Appenines, which borders 
immediately on the coast. The mountains in this portion of 
the chain are chiefly of primitive slate, with some subordi- 
nate formations of marble and serpentine, a considerable ex- 
tent of transition and secondary limestone, chiefly to the east- 
ward of Genoa, and a few more partial deposits of sandstone 
and coal. 
The summit of Monte della Guardia is somewhat more than 
2000 feet above the level of the sea, from which it is five 
* This paper was published by the Society of Medical Emulation in Genoa. 
