400 Gleanings from the International Exhibition. 



well illustrated by the soda manufactures shown in the building-. 

 Gigantic and beautiful crystals of bicarbonate of soda are exhibited 

 having the exact form of the common carbonate when crystallized 

 with ten equivalents of water. They are produced by exposing the 

 latter to the action of carbonic acid, which is absorbed, and changes 

 the chemical constitution of the substance without affecting its 

 physical form, hence results one salt having the form proper to 

 another. 



Thallium, the last New Element. — The last new element which 

 has been recently discovered, in extremely minute quantity, in some 

 ores of sulphur, by the aid of the spectroscope and process of spec- 

 trum analysis, is shown by its discoverer, Mr. Crookes ; several of 

 its compounds are also exhibited. Thallium gives a single, bright 

 green line in the prismatic spectrum, hence its name from Thallus, 

 a green branch. 



Utilization of Mixed Cotton and Woollen Rags. — A very 

 ingenious method of utilizing a waste product has been devised by 

 Mr. Ward, and is illustrated by his specimens in case 618. The rags 

 of mixed cotton and wool such as the ordinary Orleans and barege 

 and many fancy Norwich goods, are submitted to the action of 

 superheated steam, which is of such a temperature as completely to 

 char and destroy the animal fibres without effecting the destruction 

 of the vegetable tissue, which can consequently be employed in 

 paper-making, the charred remains of the wool being useful as 

 manure. 



Aniline and Coal Tar Dyes. — The production of the valuable 

 dyes derived from coal tar is illustrated by a beautiful series of spe- 

 cimens showing the various stages of the manufacture, and a block of 

 solid aniline purple, or mauve, about one thousand pounds in value, 

 containing sufficient amount of colouring material to dye hundreds 

 of miles of silks (581). These beautiful specimens are exhibited by 

 Mr. Perkins, the discoverer of the colours. Splendid specimens of 

 crystallized rose aniline or magenta are shown by Messrs. Simpson 

 and Nicholson (600). This colour, which in the solid form is of a 

 lustrous metallic green, resembling the wing-cases of tropical 

 beetles, is crystallized around wires, arranged into large crowns. 



New Process for Preserving Uncooked Meat. — Specimens 

 illustrative of Jones's process of preserving of raw meat, as joints 

 of beef, fowls, salmon, etc., aro exhibited (795). The plan adopted 

 is to extract the atmospheric air by means of a vacuum, and then to 

 admit nitrogen or azote. This permeates the substance of the flesh, 

 and prevents the putrefactive changes which would otherwise 

 ensue. 



Multiple Telegraph Cable. — The Gutta Percha Company 

 exhibit a specimen showing the perfection of their mechanism and 

 workmanship. It consists of a cable half an inch in diameter, 

 which contains forty-nine telegraphic wires, each perfectly and 

 separately insulated, and capable of conveying its own electric cur- 

 rent without influencing, or being influenced by, the currents passing 

 along the other wires. 



