SCIENTIFIC SUMMARY. 
107 
Generation of Steam and Prevention of Smoke. — Experiments in relation 
to these two points have been conducted during the past eighteen months, 
under the direction of the late Dr. E-ichardson, of Newcastle, and Mr. 
L. E. Fletcher, chief engineer to the Association for preventing Steam 
Boiler Explosions. These experiments are conducted on a large scale, and 
the expenses have been borne by the South Lancashire and Cheshire Coal 
Association. Although the experiments are not yet completed, being still 
in daily progress, they demonstrate that the formation of smoke may be 
entirely prevented, without any diminution of the evaporative efficiency of 
the coal, by careful firing alone, whilst economy is promoted at same time. 
Puballite, or Red Tourmaline. — In the Proceedings of the Royal Society 
of Victoria is a paper by the Rev. Dr. Bleasdale on this Victorian mineral. 
At the meeting at which the paper was read, Dr. Bleasdale exhibited speci- 
mens of the mineral, all of which were embedded in quartz crystals. As a 
gem, when the colour is perfect, it is said to possess great beauty. It has 
been only recently discovered. 
South African Mineralogy. — We learn from one of the Cape papers that 
the discovery of precious stones is exciting a good deal of attention in South 
Africa, owing to a little girl having recently picked up what she considered to 
be a pretty stone, which turned out to be a diamond worth 500/. Garnets have 
also been recently found in considerable numbers. It is also reported that 
silver, mercury, amber, and oil-stones have been found in some quantity. 
A Deposit of Rock-salt. — The Prussian Government has been recently 
making active researches in the kingdom to discover fresh mines of rock- 
salt. The borings, executed under the orders of Count d’ltzenplitz. Minister 
of Commerce, have now led to the discovery of a rich deposit of that mineral 
near Sperenberg, to the north of the Lake Krummsee, at a distance of twenty- 
two miles from Berlin. The salt is found at a depth of 300 feet from the 
surface. — Vide Journal of Society of Arts. 
Soluble Mineral in Preserving Stone. — One of our contemporaries expresses 
itself in high terms of praise of a process for the preservation of stone, 
which has been discovered by Messrs. Dent and Brown, of the Chemical 
Department, Woolwich. ‘‘ Their process consists in the application of a 
solution of oxalate of alumina to the stone. The experiments date from 
December, 1865, and the results they have now obtained are most encou- 
raging. The process is applicable to limestone, dolomite, and chalk, and 
may, we think, be made subservient to the preparation of lithographic stones. 
Oxalate of alumina is readily soluble in water, and the solution, which is 
simply applied with a brush, is made of a strength varying with the porosity 
of the material to which it is to be applied. The specimens we have before 
us are left in the original condition at one end, and have been prepared with 
the solution at the other. The physical characteristics of chalk so treated 
are — lightness, the possession of a glazed surface approaching somewhat in 
appearance marble, and greatly increases hardness ; in this respect the stone 
is about equal to Fluor spar, or 4 in Mohs’ scale. Furthermore, the lime 
being transformed into one of the most insoluble and unalterable of its com- 
pounds, and the alumina being precipitated, the pores are filled with a sub- 
stance almost unacted upon by water or by the impurities present in the 
atmosphere of large cities.” — Vide Chemical Neios, Oct. 25. 
