164 



"POPULAR SOIEI^OE NEWS. 



[November, 1888. 



FILTRATION WITH FILTERS OF METALLIC 

 FELT. 



Gooch's admirable Alter of asbestos felt is too 

 widely known and extensively used to require de- 

 scription, and his ingenious modification of it, in 

 which volatile felts are employed, is recognized as 

 forming a useful extension of the method for cer- 

 tain applications. Some time since, it occurred to 

 me that another modification might be wrought if 

 we were to use, for the manufacture of the felts, 

 metallic salts which were easily decomposed on 

 ignition, and which, when decomposed, left the 

 metal as a spongy, coherent residue. Such a salt 

 is found in the ammonium platinic chloride, and 

 by its use I have obtaioed the metallic felt, which 

 served very nicely for this purpose. 



To produce this filter I precipitated platinum 

 chloride with ammonium chloride, using a slight 

 excess of the reagent, and washed the salt thor- 

 oughly, first with water and then with alcohol. 

 Then, taking a Gooch filtering crucible of platinum, 

 I placed it ou a thick piece of bibulous paper, and 

 poured in the moist salt. The alcohol ran through 

 the perforations in the crucible, and was absorbed 

 by the bibulous paper, while the salt remained be- 

 hiud; the filtering crucible being filled in this way 

 to a height of about five millimeters. The crucible 

 was then carefully cleaned and dried, the cap and 

 cover put on, and the whole ignited, thus driving 

 ofi the volatile constituents, and leaving a spongy, 

 coherent residue of metallic platinum well dis- 

 tributed over the perforated bottom of the crucible. 

 In order to prevent the sponge from cracking and 

 curling, it was found essential to dry and ignite the 

 salt quite cautiously ; but in some instances where 

 cracks did appear they were easily and effectually 

 closed by gently rubbing with a glass rod, while in 

 other cases the crevices were filled with a fresh 

 portion of the ammonium platinic chloride, and the 

 drying and igniting repeated. The latter method 

 was also employed when it was thought desirable to 

 increase the thickness of the felt. After a short 

 trial the preparation of the felt became quite easily 

 and readily accomplished. The prepared filters 

 are used in the same way as Gooch's asbestos fil- 

 ters are, the caoutchouc gasket described in my 

 paper on the " Use of Porous Cones in Filtration " 

 being employed to secure an air-tight joint. The 

 platinum felt may be easily removed, when desired, 

 by means of a spatula; the small portions remaining 

 in the perforations being pushed out with the point 

 of a needle. 



I have repeatedly prepared these filters in the 

 manner above described, and have filtered with 

 them such preparations as freshly precipitated 

 barium sulphate to my entire satisfaction. Not 

 only that, but, by treating the precipitates with 

 their proper solvents, I have been able to clean the 

 feltso that the same filter could be used repeatedly. 

 — C. E. MuNROE, in Journal of Analytical Chemistry. 



HOW CELLULOID IS MADE. 



While everybody has heard of, or seen, or used 

 celluloid, only a few know what it is composed of 

 or how it is made. The following is a description 

 of the process carried out in a factory near Paris, 

 for the production of celluloid: — 



A roll of paper is slowly unwound, and at the 

 same time is saturated with a mixture of five 

 parts of sulphuric acid and two parts of nitric 

 acid, which falls upon the paper in a fine spray. 

 This changes the cellulose of the paper into 

 pyroxylin (gun cotton). The excess of the acid 

 having been expelled by pressure, the paper is 

 washed with plenty of water until all traces of 

 acid have been removed. It is then reduced to a 

 pulp, and passes on to the bleaching trough. 



Most of the water having been got rid of by 

 means of a strainer, the pulp is mixed with from 

 twenty to forty per cent of its weight in camphor, 

 and the mixture thoroughly triturated under mill- 

 stones. The necessary coloring having been added 

 in the form of powder, a second mixing and grind- 

 ing follows. 



The finely divided pulp is then spread out in 

 thin layers on slabs; and from twenty to twenty- 

 five of these layers are placed in a hydraulic press, 

 separated from one another by some sheets of 

 thick blotting-paper, and are subjected to a 

 pressure of 150 atmospheres, until all traces of 

 moisture have been got rid of. The matter is then 

 passed between rollers heated to between 140° and 

 150° F., whence it issues in the form of elastic 

 sheets. — The Inventor. 



BALLOONING WITH NATURAL GAS. 

 The first balloon inflated with natural gas ever 

 sent up arose from Riverside Park, near Ander- 

 son, Ind., Aug. 14. It has been a question as to 

 whether natui'al gas would float a balloon to any 

 considerable height, says a writer from that town. 

 This one was filled by a pipe from a well until the 

 gauge indicated that the silk, which was enclosed 

 in a strong netting, was bearing twenty pounds 

 pressure, when George Ayers, an amateur aero- 

 naut, climbed into the basket, and the balloon 

 was cut loose. It rose steadily until an altitude of 

 about twenty-five hundred feet was reached, when 

 a current of air was struck which bore the balloon 

 and its single passenger away to the south-east, 

 since which nothing has been seen or heard from 

 him. — Progressive Age. 



PRACTICAL RECIPES. 



A Flexible Cement is made by melting to- 

 gether equal parts gutta-percha and white-pine 

 pitch, which softens on the water bath, and is not 

 deteriorated by remelting. 



A Paste suitable to preserve the gloss of patent 

 leather, and prevent cracking, is made of wax, with 

 a little olive-oil, lard, and oil of turpentine, mixed 

 when warm, to be of the consistency of thick paste 

 when cooled. 



Darkening the Natural Hue of Wood. — 

 This is effected by a solution composed of equal 

 parts of manganate of soda and crystallized Epsom 

 salts, dissolved in twenty to thirty times the amount 

 of water, at about 144°. The less water employed, 

 the darker will be the hue. 



Fusible Alloy. — An alloy which melts at a 

 lower temperature than the magic spoon does is 

 obtained by melting together 48 parts bismuth, 31 

 of cadmium, 10 of lead, and 20 of zinc. This alloy 

 hielts at 135° F. 



A Solvent for Rust. — It is often very difli- 

 cult, and sometimes impossible, to remove rust 

 from articles made of iron. Those which are most 

 thickly coated are most easily cleaned by being im- 

 mersed in a solution, nearly saturated, of chloride 

 of tin. The length of time they remain in this 

 bath is determined by the thickness of the coating 

 of rust. Generally twelve to twenty-four hours is 

 long enough. 



An Incombustible Wick. — Fine wood saw- 

 dust, 4 parts; powdered fire-clay, 2 parts ; powdered 

 glass, 1 part; cotton or cotton dust, 1 part; sea- 

 sand, 6 parts. This mixture, moistened, dried, 

 and fired at a full red heat for half an hour, is 

 stated to yield a very permanent and porous mate- 

 rial for lamp-wicks. 



To remove Paint from a Wood-Carving 

 without damaging the wood, mix one part by 

 weight of pearl-ash with three parts lime by slack- 

 ing the lime in water, and then adding the pearl- 



ash, making the mixture of about the consistency 

 of paint. With an old brush lay the above over 

 the whole of the work required to be cleaned; let 

 it remain fourteen or sixteen hours, when the paint 

 can be easily scraped off. 



A French Polish can be made as follows. 

 Though rather complicated, it is worth the trouble : 

 Take one pint of soft water, and mix with it twice 

 as much vinegar; break in small pieces one-quarter 

 pound of glue ; stir it into the vinegar and water 

 with half a pound of logwood chips, a quarter- 

 ounce of finely powdered indigo, a quarter-ounce 

 of the best soap, and a quarter-ounce of isinglass. 

 Put all this mixture on the fire, and let it boil 

 gently for at least a quarter of an hour; strain it 

 carefully, put it in bottles, and cork tightly; when 

 cold it is ready to be used. A clean, soft sponge 

 should be used to apply it. 



An Elastic Mucilage. — Dissolve 1 part of 

 salicylic acid in 20 parts of alcohol, add 3 parts of 

 soft soap and 3 parts of glycerine. Shake thor- 

 oughly, and add the mixture to a mucilage pre- 

 pared from 93 parts of gum-arabic and the requisite 

 amount of water (about 180 parts). This mucilage 

 is said to keep well, and, when it dries, to remain 

 elastic without tendency to cracking. 



INDUSTRIAL MEMORANDA. 



The Contractor who laid the new railway line 

 from Philippopolis to Constantinople was, under a 

 loosely drawn contract, allowed so much per kilo- 

 meter. The result is one of the most extraordi- 

 nary zigzags ever seen in railway construction. 



AVaste Silk for Steam-Pipe Covering. — 

 Experiments on the relative advantages of differ- 

 ent covering material for steam-pipes, recently made 

 at Saint-Denis, proved waste silk the most effectual 

 of all non-conducting compositions; and it is stated, 

 that, notwithstanding its high price, this material is 

 greatly used. 



How THE Chinese Drill Wells. — The 

 French Abb^ Hue thus describes the system of 

 deep-earth boring practised in the district in which 

 he has for some time resided. A wooden tube 

 six feet in length is first driven down through the 

 surface soil. This tube is held at the surface of 

 the ground by a large flagstone, having a hole in 

 the centre to allow the tube to pass through and 

 to project a little above it. A cylindrical mass of 

 iron, weighing about four hundred pounds, hollow 

 and pointed at its lower end, and having lateral 

 notches or apertures, is jerked up and down in this 

 tube at the end of a lever, from which it is sus- 

 pended by a rope. This kind of "monkey" dis- 

 integrates the rock, the debris of which, converted 

 into sludge by water poured in , finds its way through 

 the lateral apertures into the interior of the cylin- 

 der. By raising the latter at intervals, this sludge 

 is removed from the bore-hole. The rate of boring 

 in rock of ordinary hardness is one foot in twelve 

 hours. Oi:ly one man is employed at one time to 

 work the lever, liy this means wells of eighteen 

 bundled feet deep are sunk iu about two years by 

 the labor of three men, relieving one another every 

 six hours. 



Electric Motors. — The Manufacturer and 

 Builder declares that there are atpresent no less than 

 ten thousand electric motors in use throughout the 

 United States. The uses to which these are put 

 are extremely varied; they embrace the running 

 of sewing-machines, printing-presses, and ventilat- 

 ing-fans; operating dental instruments; driving 

 street-cars; coal and ore haulage in mines; pumping 

 water; washing bottles; and in machine-shops, 

 shoe-factories, book-binderies, knitting-works, etc. , 

 for miscellaneous uses, they are becoming quite 

 common. 



