70 ANNUAL OF SCIENTIFIC DISCOVERY. 



UTILIZATION OF WASTE PRODUCTS. 



At a recent meeting of the New York Polytechnic Association, 

 Prof. Joy, of Columbia College, enumerated the following as among 

 the instances where attention to the utilization of waste material was 

 desirable : 



Waste Vulcanized Rubber. There seems to be a want of some 

 ready method of devulcanizing old India rubber. Several patents 

 have been issued for this purpose, but the fact that there is no demand 

 for worn-out articles of India rubber, would lead us to conclude that 

 this material is not utilized to any great extent. 



Slag from Iron Furnaces. At Mantsel, Germany, Prof. Joy 

 recently observed the following plan for using the slag of the furnaces. 

 The slag is formed into molds of about a cubic foot each, and distrib- 

 uted to workmen. Each man takes his share of the blocks in an iron 

 wheelbarrow and wheels them home, when they still contain heat 

 enouo-h to cook the meal for the family. After they are cooled these 



^j * ^ 



rectangular blocks are an excellent material for building walls. 



^7 ^* 



(At the last meeting of the British Association Dr. Paul stated that 

 he had succeeded in blowing the slag into a state of very fine division 

 by sending steam or air into it just as it flowed from the blast furnace 

 in a liquid state. It was thus blown into a substance resembling 

 wood in appearance. Tliis substance was taken and ground into 

 dust, mixed with lime, subjected to a powerful pressure, and made 

 into bricks, of which he exhibited some examples. These bricks 

 required no fire. After being pressed they were allowed to dry, and 

 coulJ be used at once, the influence of the atmosphere producing a 

 slow kind of hardening.) Editor. 



Zinc waited in galvanizing Iron. A large portion of the zinc 

 used for coating iron is evaporated and lost. Plans for preventing 

 this loss an- worthy of the attention of inventors. The whole history 

 of zinc is taat of a waste product. It was iirst found in chimneys 

 where ores of other metals were being smelted and people were thus 

 led to seek for it in its own ores. 



Waste from Gas-works. Constant progress has been made in the 

 utilization of the waste substances produced in the manufacture of 

 illuminating gas. At one time the companies paid persons for carting 

 away the li.ne used for purifying the gas. The lime absorbs bisul- 

 phide of carbon, sulphuretted hydrogen and sulphur, coining from the 

 distillation of the coal, and when exposed for a long time to the 

 atmosphere' it absorbs oxygen and becomes the sulphate of lime or 

 plaster. Tliis is MOW understood by a sufficient number of farmers to 

 make a dem.md for the waste lime at a moderate price. 



.Mr. Clel.md, the Director of the Liverpool Gas Works, states that 

 he has largely reduced the cost of purifying gas by using oxide of 

 iron, and saving the sulphur and ammonia. The material from the 

 purifiers is heated to about 1,000 Fahrenheit in a close iron retort. 

 A portion of the sulphur combines chemically with the iron, while the 

 balance- is distilled over. As soon as the sulphur ceases to come over, 

 the content ; of tin- retort are drawn and moistened, and in this state 

 exposed to l he action of the atmosphere. The oxidation is rapid, and 

 the mass glows until frequently wet and >lirred. In a lew weeks a 



