548 Progress in Science. [October, 



TECHNOLOGY. 



The difficulty of uniting iron to brass is caused by the unequal rate of expan- 

 sion in the two metals, which destroys the unity when the temperature is 

 changed. A new alloy of copper is announced, and the inventor claims that 

 its expansion by heat is so similar to that of iron and steel, that the surfaces 

 may be regarded, when joined, as permanently united, for all practical purposes. 

 The formula is as follows: — Tin, 3 parts; copper, 39^ parts ; zinc, 7I parts. 



A new plan for meat preserving has been been introduced by an engineer, 

 whose experience in sugar refineries and other extensive works in hot latitudes 

 has ensured a practical and economical solution of one of the most important 

 problems of .the day. Mr. T. F. Henley does away with steeping meat in 

 water, and with boiling and otherwise treating it in the most costly way. He 

 simply squeezes a definite amount of juice out of the fibre, and by mechanical 

 desiccation preserves the latter intact. The pressed meat thus obtained con- 

 tains 10 per cent of alcoholic extract and salt, and over 50 per cent of fibrin 

 and o^her albumenoid constituents. It is exceedingly rich, and so is the 

 meat-juice, which Mr. Henley evaporates in vacuum pans. The juice contains 

 about 15 per cent of alcoholic extract, and over 50 per cent of albumen. The 

 ancient method of abstracting water only from the animal matter is relied on 

 as the preservative, and the low temperature at which the evaporation is 

 carried on prevents any loss of flavour or other deterioration. It is perhaps 

 strange that so cheap and simple a process should not have been suggested 

 before. Mr. Henley has worked at it for some time, and perfected it so as to 

 ensure its immediate adoption. The first works, on an extensive scale, are to 

 be opened in the River Plate, on the Estancia Nueva Alemania, where cattle have 

 been reared and fattened for the European markets. 



Acetate of alumina has been found very useful for the purpose of rendering 

 woven fabrics waterproof without thereby impeding the passage of perspira- 

 tion. Professor Balard prepares the acetate of alumina by dissolving 30 grms. 

 of acetate of lead in | a litre of water, and also 24 grms. of sulphate of 

 alumina in | a litre of water. These solutions, having been mixed, are next 

 filtered, after which the fabric is immersed therein for a quarter of an hour, 

 and, after having been well drained, is dried in the air. 



Dr. E. Kopp has published a lengthy memoir containing, in a condensed 

 form, all the information on the subject of distinguishing silk, wool, and 

 vegetable fibres from each other, and also the various methods employed on 

 the large scale for separating animal and vegetable fibres when they occur in 

 mixed fabrics. Among some of the particular reactions we find the following 

 for detecting wool in silk, and vice versa, based upon the fact that wool con- 

 tains sulphur, while silk does not. The tissue to be tested — it should be, 

 however, white, not dyed — is put into a solution of caustic potassa or soda, 

 wherein oxide of lead has been previously dissolved ; woollen fibres become 

 black when immersed in this liquor, whereas silk remains unchanged. Another 

 test for the same purpose is ordinary nitric acid, which dissolves silk in the 

 cold, but hardly affects wool. 



The following mixtures have been found, after a series of experiments, to be 

 the best for red, green, and blue Bengal lights : — For red, 9 parts of nitrate of 

 strontia, 3 parts of shellac, i| parts of chlorate of potassa ; for green, 9 parts 

 of nitrate of baryta, 3 parts of shellac, i£ parts of chlorate of potassa ; for blue, 

 8 parts of ammoniacal sulphate of copper, 6 parts of chlorate of potassa, 1 part 

 of shellac. This latter ingredient need only be coarsely pulverised. The 

 mixtures here alluded to are suitable for use in theatres and rooms, as by the 

 combustion no injurious vapours are given off. 



Dr. F. Springmuhl has described a series of experiments made with the view 

 to ascertain how far, and under what conditions, sodium may be employed as 

 a substance suited to cause, by contact either with water or other materials, 

 the explosion of vessels wherein these substances are contained. The force 

 exerted is by no means small, as may be inferred from the following : — 46 grms. 

 of sodium and 18 grms. of water yield 2 grms. of hydrogen, a bulk of 22471*9 

 cubic centimetres. The space required for the sodium only amounts to 447 



