564 
"October, 
Progress in Science. 
silicate, more friable, and containing 12 to 15 per cent of nickel and 10 to 15 
o: water; a whitish blue hydrosiucate, very brittle, and easily crushed with 
the hngers.^ containing merely 6 to S per cent of nickel, and as mucn as 20 
percent ot water. I he metallic nicxel extracted from these ores contains 
from gS to 99-5 per cent of pure nickel. 
Tne Mineralogical Society of Great Britain and Ireland has issued the first 
number 01 its journal. A meeting of the society was held at Redruth on 
July 1st, wnen the secretary, Mr. J. H. Collins, read^ a paper on a new 
mineral from Yv es: Pnoenix Mine which he has named “ Henwoodice.” It is 
a hydrous phosphate o: alumina and copper, resembling turquoise, but con- 
taining more phospnoric acid and water and less alumina. Dr. C. Le Neve 
Foster read a paper on the occurrence of pyrophillite at Brookwood Mine, 
ana on new mineral localities in Devon and Cornwall, in which he described 
a new mineral “ Enysite," a hydrated compound of alumina and copper, with 
some sulphates, carbonates, and chlorides. 
Mr. William Vivian contributed a note on paragenetic formations of carbo- 
nate of lime and oxide of iron, and of quartz, at the Mwyndy Mines, 
Glamorganshire. These specimens form interesting objects for the microscope, 
they are best seen as opaque objects in a good light and with a low power 
from 1 to 2 objectives. Mr. Collins remarked that these constant occur- 
rences strengthen the evidence already existing that such iron ore deposits as 
that at Mwyndy, like those in the lodes or cross-courses of Cornwall and 
Devon, are due to infiltration of ferruginous matter from the surrounding 
rocks into pre-existing fissures. 
At the same meeting Mr. Collins noted the occurrence of scorodite, pharma- 
cosiderite, and olivemte in greenstones at Terras Mine, St. Stephens, and Dr. 
Foster exhib ted a new form of blowpipe lamp suitable for travellers. 
A meeting of the society was held in Glasgow on September 6th, when 
Professor Heddle delivered an address “ On Scotch Minerals, how and where 
to find them.' 5 
Dr. Haughton, of Trinity College, Dublin, delivered an address on a new 
principle in tre consolidation of porphyritic rocks. He received a collection 
of lava from Vesuvius, with the view of ascertaining if, in the space of 300 
years, any difference had occurred in the composition of the lava flows. In 
the course of the investigation he ascertained that the minerals combined 
with a substance like paste, and his researches led to the conclusion that 
when a rock crystallises the maximum of minerals will form with a minimum 
of paste ; this “ principle of least paste ” is confirmed by chemical experi- 
ments. 
The Secretary read a paper by the president, Mr. H. C. Sorby, “ On the 
Critical Point in the Consolidation of Granite.' 5 In the opinion of the author 
the critical point in the consolidation of granite is very closely connected with 
the critical temperature at which highly heated and compressed steam con- 
denses into an equal volume of highly heated and expanded liquid water. 
Rocks melted under great pressure probably contain water either dissolved as 
a gas in a liquid or in the state of a fused hydrate. On cooling down to a 
lower temperature the crystallising out of minerals almost necessarily sets 
free the previous!} 7 combined water. As long as the temperature is above the 
critical point it necessarily remains more or less disseminated in the rocks as 
a highly compressed steam, but as soon as the temperature falls below the 
critical point it condenses into highly expanded liquid water. The only deter- 
mination of this temperature with which the author is acquainted is that of 
Cagmard Latur, who found that water expanded to nearly four times its 
volume, and passed into an equal volume of highly compressed steam, at 
about the melting point of zinc, or4i2 = C. As long as the temperature is 
higher than this the solvent action of water cannot he brought into play, since 
earthy substance and alkaline salts cannot be dissolved in steam ; but as soon 
as it condenses into a liquid the solvent power of the water will be very great, 
as shown by its intense action on glass. These theoretical deductions agree 
remarkably well with the microscopical structure of the Pouza granite. 
