June 1st, 1SS7.] 



SCIENTIFIC NEWS. 



the shores of the Baltic, gum mastic from the island of 

 Chios, gum animi from Zanzibar and Demerara, and 

 gum kaori from New Zealand. The last named weighs 

 about 200 pounds, and is the largest specimen yet dis- 

 covered ; the gum animi from Demerara is also particularly 

 interesting, as it has embedded in it a large number of ants 

 and other insects. 



In the metallurgy group Mr. Percy C. Gilchrist has a 

 good collection of steel and slag made from phosphoric 

 pig-iron by the Basic or Thomas-Gilchrist process, and 

 in the same group the College of Agriculture, at Downton, 

 exhibit a chart showing the effects of basic cinder used 

 as a fertiliser. This subject, however, will be treated of 

 in our next issue in a separate note, kindly sent us 

 by a professor of the college. The Magnesium Metal 

 Co. have a veiy interesting and choice collection of 

 antimony, bismuth, magnesium, quicksilver, potassium, 

 sodium, vanadium, and other rare and interesting metals. 

 Their manufactured products are also well worth examina- 

 tion. Messrs. J. Walktr, Parker and Co. show specimens 

 of lead ore, and of the products and manufactures for which 

 they have such a deservedly high reputation. A novelty 

 shown by them is an oval pipe for resisting the effect of 

 trost, and specimens are exhibited of round and oval pipes 

 of the same size, which have been subjected to the same 

 freezing temperature. The round pipe burst after two or 

 three freezings, but the oval pipe resisted many more 

 freezings before showing signs of injury. Messrs. H. Wig- 

 gin and Co. show specimens of nickel and cobalt ores from 

 Hungary, Norway, and New Caledonia, also articles pro- 

 duced from them in various stages of manufacture. They 

 also show some fine specimens of the oxides of cobalt used 

 in the potteries for obtaining a beautiful blue colour; they 

 also have a new substance, carbonate of cobalt, used in the 

 arts, and a soluble oxide of nickel used for making nickel 

 salts. 



Among the Alkalis and Acids, Messrs. J. Riley and Sons 

 show samples of sulphuric acid made from brimstone, and 

 to get it pure they concentrate it in platinum vessels 

 instead of lead. Specimens of these vessels are shown in 

 an adjoining case by the makers, Messrs. Johnson, Matthey 

 and Co., and are specially deserving of attention. Messrs. 

 Gaskell, Deacon and Co. have a fine set of samples of their 

 special make of crystallised carbonate and bicarbonate of 

 soda made direct from the vat liquor, besides other 

 chemicals used for bleaching and washing. Messrs. Bell 

 Brothers show samples illustrating the salt deposits and 

 industry of the Tees, an account of which will be found 

 in Sir Lowthian Bell's paper just read at the Institution of 

 Civil Engineers. Messrs. Peter Spence and Sons have a 

 really fine display of alum, such as is used by paper 

 makers, dyers, calico printers, pottery colour manufacturers, 

 and others : also sulphate of alumina and some special 

 compounds used by dyers and others. They also exhibit a 

 proposed international hydrometer, to be used as a standard 

 measurer both of the strength and the specific gravity of 

 solutions and other liquids. We hope to give a more de- 

 tailed description of this another time. The Widnes Alkali 

 Co. show fine specimens of their well-known caustic soda, 

 bleaching powder, etc. The caustic soda trade is another 

 instance of remarkable development : within the last 

 twenty-two years it has increased from about 100 tons a 

 week to about 3,000 tons a week. The Widnes Co. alone 

 make about 650 tons a week, and have three of the largest 

 revolving furnaces in the world. Caustic soda is chiefly 

 used by paper makers and in the manufacture of soap. 

 Wood pulp is also used by paper makers as a substitute for 

 rags, and Messrs. Newall and Son show specimens made by 

 grinding the wood mechanically ; they also make pulp by 



treating the wood with caustic soda or other chemicals, and 

 these processes are preferred to the mechanical one. The 

 wood is chiefly imported from Norway and Sweden. 



In conclusion, we strongly recommend our readers to in- 

 spect this very important section of the exhibition. It is 

 impossible for us to deal thoroughly with the very varied 

 collection it contains, but the examples we have cited are 

 sufficient to show how much there is to interest not only 

 the chemist, but others who desire information on many 

 important branches of our national industries. 



Mkntal Work. — There is as much danger of hurting the brain 

 by idleness as by overwork, for intellectual power is lessened 

 by the listlessness in which the well-to-do classes so often spend 

 their lives. Under such conditions the brain gradually loses its 

 health, and although equal to the demands of a routine exist- 

 ence, it is unable to withstand the strain of sudden emergency. 

 When therefore work is unexpectedly thrown on it in its un- 

 prepared state, the worst consequences of what may be called 

 overwork show themselves. .Similarly, a man accustomed to 

 sedentary pursuits is liable to be physically injured by suddenly 

 taking too violent exercise. As to the amount of mental work 

 that may be safely done. Dr. Farquharson says : — " So long as a 

 brain worker is able to sleep well, to eat well, and to take a fair 

 proportion of out-door exercise, it may safely be said that it is 

 not necessary to impose any special limits on the actual number 

 of hours which he devotes to his labours. But when what is 

 generally known as worry steps in to complicate matters, when 

 cares connected with family arrangements, or with those nume- 

 rous personal details which we can seldom escape, intervene ; 

 or when the daily occupation of life is in itself a fertile source 

 of anxiety, then we hnd one or other of these three safeguards 

 broken down." 



APPARATUS FOR COMPRESSING OR 

 EXHAUSTING AIR. 



THOSE of our readers who are accustomed to laboratory 

 work are well aware that it is frequently necessary to 

 compress or exhaust air for certain operations. For in- 

 stance, a blow-pipe requires a supply of air at pressure, and 

 this is produced either by the mouth, by a foot-blower, or 

 by mechanical means. When suction is required, an 

 aspirator is generally used, as shown in Fig. i. In this the 

 vessel A is first charged with water by taking out the 

 stopper 5/ the stopper is then replaced, and the tube / is 

 connected with the apparatus to be exhausted. If the cock 

 c is then opened, and water is allowed to run out, the pres- 

 sure within the vessel A is reduced below that of the 

 atmosphere, and a suction is caused in the direction of the 

 arrow e. This is suitable for operations of short duration, 

 in which very little power is required ; but for many pur- 

 poses it is insufficient, and an expensive pneumatic appara- 

 tus is necessary. 



In a recent number of La Nature, attention was called to 

 an apparatus made by M. Alvergniat, of Paris, in which use 

 is made of a continuous stream of water at the pressure 

 obtained from the street mains, for the purpose of exhaust- 

 ing or blowing. This apparatus is shown in Fig. 2, and 

 may be thus described : When the tap a is opened water 

 from the main passes through the two cones b and c and 

 then into the vessel A through the tube /; the cock g 

 should then be opened, to allow the water to pass, and it, 

 at the same time, the cock d is open, air will be sucked in 

 and carried forward by the water into A. The principle 

 is, in fact, that of the well-known injector, in this case 

 worked by water instead of steam. The air, being lighter 

 than the water, rises to the upper part of A, and, as the 

 water is under pressure, it in turn compresses the air. If 

 the cock e be opened, there will therefore be an escape of 

 air at pressure, and this can be used for blow-pipe or other 



