540 SEC. 13. CHEMISTRY. 



2738f. Examples of Technological Diagrams. 



Diagram 6. Retort for the manufacture of coal gas. 



?J ' 5> t) 



)y 28. Extraction of zinc (Silesian furnace). 

 31. Lime-kiln (continuous process). 

 32. Lead smelting (German cupellation hearth). 

 36. Lead smelting blast furnace. 

 37. Extraction of salt by evaporation of brine. 

 38. Graduation house. 



50. Manufacture of steel evaporating pans by cemen- 

 tation. 



The Council of the Yoi'kshire College of Science, Leeds, 

 Professor Thorpe. 



2458. Gay Lus sac's Apparatus for assaying Silver by 

 the Wet Way. Aug. Bel and Co. 



Copper cistern lined with resinous cement to contain the normal solution of 

 salt, 100 standard measures of which correspond with 896-thousandth of fine 

 silver in the assay. Funnel for use in filling the cistern. Pipette of 100 cc, 

 for use with normal solution. Pipette for use with decimal salt solution. 

 Pipette for use with the decimal silver solution. Cage for conveying the hottles 

 to the shaking apparatus. Shaking apparatus, filled with 10 assay bottles in 

 position for use. Dark case for bottle, containing the decimal silver solution. 

 Case in which the assay bottle is placed during the addition of the normal 

 solution to the assay. Hollow pillar, with sponge for absorbing the excess 

 of liquid from the front pipette during the adjustment of the level to gauge 

 mark. Water bath used for heating assay bottles during the solution of 

 assay pieces. Bellows used for removing the nitrous fumes from the assay 

 bottles. Whisk used for stirring the salt solution in the cistern. 



V. APPARATUS ILLUSTRATING AGRICULTURAL 

 CHEMISTRY. 



2741. Specially made Balance, and other appb'ances, used 

 in an investigation by Messrs. Lawes and Gilbert, to determine the 

 amount of water given off by plants during their growth. See 

 Journal of the Horticultural Society of London, vol. v., p. 38, 

 1850, and vol. vi., p. 227, 1851. The experiments were, however, 

 continued to 1858, inclusive. John Bennet Lawes. 



The balance, which was made by Mr. Oertling, of London, was constructed 

 to turn with less than one grain, when loaded with 50 Ibs., or even more, on 

 each side. This it accomplished, but it was found that the quantity of water 

 given off by the plants during their growth was so great that such accurate 

 weighing was not necessary. In fact, during the whole period of growth, as 

 much as from 15 to 20 Ibs. of water was in some cases given off from a single 

 jar of plants, and during the most active periods of growth as much as from 

 1,500 to 2,000 grains per day. In the earlier experiments the vessels in 

 which the plants were grown were made of glass, but afterwards of zinc. 

 There was no opening at the bottom for drainage. The top was closed by a 

 glass plate, firmly cemented to the rim, but having a hole in the centre for the 

 plants to grow through, and another smaller one nearer the side by which to 



