258 Correspondence of O. C. Marsh. 
of especial interest. The display of tin, bismuth, and titanium was quite. 
small, the only representations of the last metal being a few rutiles from 
e well known Georgia locality. 
lopper—Copper ores from nearly every part of the world were exhib- 
ited in this class; some of the most interesting specimens were very fine 
erystals of the native metal from Lake Superior, boulders of vitreous cop 
per from a serpentine (“gabbro” of the Italians) dyke at Monte Catani in 
Val di Cecini near Volterra, in Italy, and a series of the Hungarian gray 
copper ores containing about ten per cent of mercury. 
New Metals.—In the French department, the new alkali metals, caesium 
ubidium, with some of their salts, were shown ; and also the new 
metal thallium,® the latest result of spectrum analysis. Manganese, ob- 
tained by a new process, was the most interesting object in Class J, of 
the Swiss department. : 
ron and Steel.—lron was naturally the most prominent object 1m an 
exhibition like the present, and no small part of the building was occupied 
by its various ores, illustrations of its Metallurgy and its applications 
Although this collection was far superior in many respects to any hitherto 
ade, the recent progress it indicated was rather, greater facilities for the 
production and application of this metal, than auy new scientific informa 
tion in regard to it. The chemistry of iron seems still to remain compa! 
atively unknown. In the British department, some rolled plates for ships 
were fine illustrations of iron manufacture. The largest of these was 13 
tons in weight ; and the shattered fragments of those broken in the recent 
iron possible is most efficacious in resisting hea e exh etal 
contained many fine specimens of steel made by Bessem rocess, whic 
seems likely to supercede many now in use. e display of cast steel by 
rupp of n, Prussia, has never been equalled his esp 
weighed 21 tons, and an examination indicated that its structure was up 
form throughout. in 
Coal artesian boring—Different varieties of coal were show? 
great profusion in Ciass I, but do not require comment. The grea i 
of this substance in the usual methods of mining is now attracting rae 
attention, especially in England, and processes for rendering the s™ | nee 
available for fuel were abundant in the exhibition. ‘These were either 
strata, in searching for coal, or in making artesian wells, formec 
structive series in the French department. It was exhibited by Deger™ 
author of “Guide du Sondeur,’ one of the best works on the subject. > 
ian collections: asterism in Mica.—Among other interesting © 
* Exhibited by Mr. Crookes also in the English Department. 
