SCIENTIFIC SUMMARY. 105 
analysis of tlie above three minerals. Beyond this the paper has little 
interest. 
A Concrete which has several good Properties . — The Rev. H. Highton, M.A., 
has described to the British Association a form of concrete which appears 
inexpensive and useful. The following is the method of preparing it : — A 
concrete is made with any good hydraulic cement. When this is dry it is 
steeped in an alkaline solution of silica, in which is placed a quantity of free 
silica. The following chemical process then takes place : the lime in the 
concrete extracts the silica from the solution, leaving the alkali free, which 
immediately attacks the free silica and conveys it in its turn to the concrete. 
This process goes on continually till the lime in the concrete is saturated 
with silica. By this process within a week the strength of the concrete is 
increased from 50 to 150 per cent., and by a longer continuation of the 
steeping the strength is still more increased. As the alkali acts only as a 
earner of the silica, it is used over and over again ; and it is in this that the 
economy of the manufacture consists. The following is the comparative 
resistance to a crushing force of several kinds of stone : — 
Per sq. inch. 
lbs. 
The Silicated Concrete, or Patent Victoria Stone . 6,441 
Aberdeen Granite . . . . . . . 7,770 
Dartmoor Granite 6,993 
Peterhead Granite 6,216 
Yorkshire Landing 5,851 
Stafford Blue Brick 4,032 
Portland Stone 2,426 
Bath Stone 1,244 
The stone formed in this manner has been tried as a pavement in the 
busiest part of Cheapside, and in many other parts of London, and for steps, 
lintels, sills, &c., in many parts both of this kingdom and abroad, as well as 
in India. The whole of the stone in the new warehouses, 27 St. Mary Axe, 
is made in this manner. 
Alloy of Lead and Platinum . — The 11 Chemical News ” gives the follow- 
ing account of the above alloy, prepared by Herr A. Bauer, which originally 
appeared in the 11 Berichte der Deutschen Chemischen Gesellschaft zu Berlin,” 
No. 15, 1860. After referring to the observation of M. Deville, that an 
alloy of lead and platinum is readily decomposed in consequence of the 
conversion of the lead into white-lead, the author made an alloy, consisting 
of 3 parts of pure lead and 1 part of platinum. This alloy is so brittle that 
it can be readily pulverised ; and the powder so obtained was moistened 
with water, and placed under a bell-jar exposed to the action of carbonic 
acid, oxygen, and vapours of acetic acid. The conversion of the lead into 
white -lead took place rapidly ; and after it appeared that all the lead was 
converted into white-lead, the powder was treated with acetic acid, and 
the residue again exposed under the bell-jar to the action of the same sub- 
stances. This process having been repeated several times, there remained 
at last a steel-greyish coloured crystalline powder, which only appeared to 
be finely divided platinum. On being treated, however, with dilute nitric 
acid, the author found that the powder consisted of an alloy of lead and 
