150 



POPULAR SCIETsTCE NEWS. 



[October, 1889. 



densing the subtle bisulphide of carbon vapor 

 were too great to make the process an eco- 

 nomical one, and it was finally given up. It 

 is as difficult to find a substitute for water in 

 steam boilers as it is to improve upon it as a 

 beverage for use in that still more wonderful 

 machine— the human body. 



In writing this article, an ingenious swindle 

 is brought to mind, which appeared a few 

 years ago, and which consisted in the alleged 

 discovery of a wonderful substance which 

 would reduce the boiling-point of water much 

 below the usual temperature, thus eiiiibling 

 steam engines to be run with a much smaller 

 expenditure of fuel. Of course no such sub- 

 stance exists, but even if it did, the natural 

 laws considered in this article would forbid 

 its being of any economical value. 



gether by electricity after being placed in position. 

 A dynamo propels over the ti-acks an electric weld- 



wheels, causes the car to move gently forward sev- 

 eral feet — the car, in fact, following the horses up. 



machine, which welds the rails into one contin- The apparatus, when being wound up, acts as a 



A NEW PHOTOGRAPHIC CHEMICAL. 



A RECENT number of the Moniteur de la Pho- 

 tographic calls attention to pyrocatechin as an 

 important new developing agent for gelatine- 

 bromide plates. Pyrocatechin, of which the formula 

 is C6H8O2, evidently belongs to the same class of 

 substances as hydroquinon, Ct^UOi, which is now 

 in daily use as a means of developing the picture on 

 gelatino-bromide plates. In Germany it has been 

 recommended for some time past as a capital sub- 

 stance for this purpose, and quite recently Dr. 

 Arnold, of Berlin, has made some experiments with 

 it, which leave no doubt in his mind that pyrocate- 

 chin is well worthy of the attention of photogra- 

 phers, as it possesses several great advantages over 

 the other substances used for the same purpose. 

 The negatives obtained by it are of a color which 

 facilitates printing; the plates do not fog, and as 

 soon as they are placed in the developing solution they 

 lose their seitsitivencss to light, so that they may be 

 developed at a distance of 20 inches from a gas 

 flame, or in weak diffused daylight. Even at a 

 comparatively low temperature this new agent acts 

 with energy. The solution does not stain the fin- 

 gers, and it gives very fine negatives, though its 

 action is not so rapid as that of pyrogallic acid. 

 Dr. Arnold uses it in conjunction with a little car- 

 bonate of potash. The formula he adopts is this: 

 Dissolve I gramme of pyrocatechin in 100 grammes 

 of water, and 20 grammes of carlwnate of potash in 

 another 100 grammes of water. To develop an 

 ordinary plate, i cubic centimetre (about 16 drops), 

 and c, to 10 cc. of the carbonate of potash solution 

 are added to 60 or 80 cubic centimetres (grammes) 

 of water. For instantaneous pictures the quantity 

 of pyrocatechin solution may be increased to 5 

 cubic centimetres. The action is very uniform. 



RAILROAD NOTES. 



The Schoolmaster Aiiroad. — The Russians 

 have recently improved on the sleeping-coaches of 

 the railway and the perambulating schoolmaster of 

 the rural regions. They have provided a school- 

 wagon, which is furnished with a room for the 

 teacher, a classroom or study, and a library, all 

 suitably supplied with the necessary material. 

 This wagon will be on the line of the Transcaspian 

 Railway all the year round, remaining as long as 

 may be deemed necessary at districts which are not 

 provided with a school. 



Electric Welding of Rails. — Prof. Elihu 

 Thomson has perfected an invention by which the 

 rails of street or steam railways may be welded to- 



uous line after it passes over them. It is proposed 

 to have at every 100 feet a break, to allow for expan- 

 sion. Any kind of rails can thus be welded, and in 

 the event of such operations in the West End lines 

 in Boston, power can be obtained from the wires 

 now in use, as but a 500 voltage will be required. 



English Railway Speeds. — The great lines of 

 railway fietween London and the north arc renew- 

 ing their racing exploits of last year's travel. This 

 year speed is kept up beyond Edinburg and Glasgow, 

 Aberdeen being included in the racing. A train 

 leaves the Granite City at 6.15 in the morning, and 

 by the western route reaches Euston at 7 in the 

 evening. The journey of 540 miles in the time 

 specified, inclusive of halts by the way, has actually 

 been accoinplished, and no doubt the locomotives 

 will continue to do their work. On the Great 

 Northern, North-Eastern, and North British lines, 

 by the east coast route, the advertised time is four- 

 teen hours less ten minutes, but as that route has 

 superior advantages of gradient and directness, it is 

 pretty certain that the engine-drivers upon it will 

 be required to work up to the standard of speed set 

 by the rival system. It is a competition of doubtful 

 value to the public. 



English Compound Locomotives. — Experience 

 with the English locomotive which the Pennsylvania 

 road brought over, and which has been undergoing 

 tests for several months, according to a Pittsburg 

 paper, will probably result in something valuable, 

 though it is not probable that the English machine 

 will ever be adopted as a whole. Of late it has been 

 running from Long Branch to New York, and is 

 becoming better liked every day for its improving 

 performances. The final test will soon be made. 

 If these experiments prove, what is generally be- 

 lieved by engineers now, that the compound type 

 will produce considerably more power at less cost 

 than the styles of engines at present in use, then the 

 compound system will be adopted at once by the 

 Pennsylvania company and applied to all its loco- 

 motives as rapidly as possible. It is likely to be a 

 year, however, before such a step is fully determined 

 upon. One thing that has been discovered in the 

 use of the "Pennsylvania" in regular service is that 

 an English locomotive won't stand the wear and 

 tear of American tracks. The engine is too rigid 

 and provided with too short springs to make an 

 easy runner over our roads. The racking it gets on 

 rough bits of track makes necessary frequent trips 

 to the shops for trifling repairs. 



Every time a horse-car is started from a state of 

 rest — and this happens many times during every 

 journey — a distressing strain is put upon the horses, 

 which tells upon them and makes horse-flesh a very 

 heavy item of expenditure. Several unsuccessful 

 attempts have been made to produce a mechanical 

 contrivance which would assist the horses by im- 

 parting an initial motion to the car at the moment 

 of starting. This is now satisfactorily accomplished 

 by a starter which has been in use for the past six 

 months on a car belonging to the Southwark and 

 Deptford Tramway Company of PJngland. The 

 apparatus consists mainly of a coiled spring in con- 

 nection with a clutch arrangement and a spud on 

 the driver's platform. A simple movement of the 

 driver's foot will throw the apparatus into or out of 

 gear, and one revolution of the car wheels is sufli- 

 cient to charge the spring for the purpose of restart- 

 ing. On starting the car, the first forward move- 

 ment of the horses causes tension on the traces and 

 at once releases the spring, which, acting upon the 



powerful brake ; it can be used as an emergency 

 brake, and can be operated from either end of the 

 car. 



PRACTICAL RECIPES. 



Strips of Gelatin^ plunged into varnish which 

 contains water, and gives a dull soft surface on dry- 

 ing, have 'the efl'ect of subtracting the greater part 

 of the water, and causing the varnish to give a bril- 

 liant and clear surface up to the last drop. 



To LicyjEFY Carbolic Acid, fill the space at the 

 neck of the bottle (new) with alcohol, and then 

 invert the spirit, which will work upward and dis- 

 solve the acid. In microscopical work, or, indeed, 

 in any other kinds, the spirit will do no harm, as it 

 will soon evaporate. 



To Remove Old Paint. — Shake three pounds of 

 quicklime in water and add one pound of pearl-ash, 

 making the whole into the consistence of paint. 

 Lay this over the old work with a brush, and let it 

 remain from twelve to fourteen hours, when the 

 paint will be easily scraped off. 



Parchment Paper may best be softened by 

 spreading or rubbing with or dipping into a mix- 

 ture of glycerine and calcium chloride, which will 

 affect not merely the surface, but enter the pores. 

 The distinctive indifferent character of the paper is 

 not altered, as by oil, which causes a stiffening of 

 the paper, only to be softened by heat. 



LiquiD Glue possessing great resisting power, 

 and particularly recommended for wood and iron, is 

 prepared, according to Hesz, as follows : Clear 

 gelatine, 100 parts; cabinet-makers' glue, 100 parts; 

 alcohol, 25 parts; alum, 2 parts; the whole mixed 

 with 200 parts of 20 per cent, acetic acid, and heated 

 on a water-bath for six hours. An ordinary liquid 

 glue, also well adapted for wood and iron, is made 

 by boiling together for several hours 100 parts glue, 

 260 parts water, and 16 parts of nitric acid. 



To Split Paper. — There are two ways of splitting 

 a piece of paper. One is to lay the sheet of paper 

 on a piece of glass, soak it thoroughly with water, 

 and then press it smoothly all over the glass. With 

 a little care the upper half of the sheet can be peeled 

 off, leaving the under half on the glass. Let this 

 dry and it will come oflf the glass easily ; of course 

 the glass must be perfectly clean. The second way 

 is a better one, but it requires some good practice. 

 Paste a piece of cloth or strong paper on each side 

 of the sheet to be split. When it has thoroughly 

 dried, pull the two pieces of cloth apart suddenly 

 and violently. The paste can then be softened with 

 water, and the two halves of the sheet easily taken 

 oft" the cloths. 



Professor Winchell's Paste. — Professor Alex. 

 Winchell has a cement that will stick on any thing. 

 The receipt is as follows : Take two ounces of clear 

 gum arable, one ounce and a half of fine starch, and 

 one half ounce of white sugar. Pulverize the gum 

 arable, and dissolve it in as much water as the laun- 

 dress would use lor the quantity of starch indic.ited. 

 Dissolve the starch and sugar in the gum solution. 

 Then cook the mixture in a vessel suspended in 

 boiling water, imtil the starch becomes clear. The 

 cement should be as thick as tar, and kept so. It 

 can be kept from spoiling by dropping in a lump of 

 gum-camphor, or a little oil of cloves or sassafras. 

 This cement is very strong indeed, and will stick 

 perfectly to glazed surfaces, and is good to repair 

 broken rocks, minerals, or fossils. 



