The Optical Magic Lantern Journal (December 1900)

160 The Optical Magic Lantern Journal and Photographic Enlarger. moderately strong reducer the upper portion of the uniformly dark sky (which may, if desired, be artificially darkened by a process similar to | that known as “ sunning down” in printing on paper) leave cloud masses of any desired form above the horizon, and then by outlining the edges with a fine brush charged with the saturated solution of ferridcyanide as described above, produce the effect co beautifully described by Tennyson in ‘In Memoriam XV.” of the cloud that “ Topples round the dreary west, A looming bastion fringed with fire.” If the slide, either by development or by subsequent toning, is rendered in a suitable colour, the result will be very fine. It may be said by some that these methods are not purely photographic, and may be therefore condemned as illegitimate ; but I think that the days of absolute purism are over, and as our pictorial photographers resort to all manner of dodges—double printing, sunning down, shading certain portions of their negatives while printing, applying matt varnish and scraping it off where needed, stumping, or chalk or blacklead, etc.—we need not hesitate to use any methods that we can devise to introduce pictorial effects into our lantern slides. The long dark evenings of winter are upon us now, and the manufacture of lantern slides and the improvement of them by various dodges will be interesting work: and the adoption of these devices will make a pleasant change in the monotony of the work of simply printing and developing transparencies for the lantern in the ordinary way. Calcium Carbide at the Congress of Applied Chemistry. MONG the papers read at the International Congress of Applied Chemistry, recently held at Paris, those relating to the carbide of calcium industry and the production of acetylene were of great interest. The present development of the car bide industry in Europe was shown by a series of papers read by different delegates, each of which described the carbide plants of one of the leading countries. M. Minet, in his opening paper, in which he treats electrochemical processes from a historical and an industrial point of view, mentions the carbide industry in a gendral way, and gives a reswmé of the installations in Europe. The paper read by M. Gin gives some interesting details as to. the development of the carbide industry in Austria-Hungary, where the abundance of waterfalls has led to the establishment of a considerable number of carbide plants. At present seven large plants are in operation, and the total water-power used is about 24,000 horse-power. A number of projects are shortly to be put into execution, which will bring the total up to nearly 80,000 horse-power. The largest of these works, from the point of view of capacity, says the Scientific American, is that of Jaice, which has been erected by the Bosnian Electric Company, the large falls of the River Pliva are here utilised. The river widens into a lake, which discharges into a lower lake in a series of cascades. The dam has been placed shortly below the mouth of the upper lake, where the water is taken off in a canal about two miles long; the canal passes through 15 tunnels of 12 by 15 feet section, and ends in a large reservoir near the station. From this point the water is brought to the turbines by two iron conduits of 5 feet diameter. The capacity of the hydraulic plant is about 9,500 horse-power. Hight turbines are installed in the station, of 1,000 horse-power each, connected to Schuckert dynamos. The electric furnaces for this plant have been installed by the latter company. The plant situated at Paternion is of much smaller capacity, but presents many points of interest. It has been installed by the Venetian Electrochemical Society, and is located on the bank of the River Kreuznerbach. The lime is furnished by quarries of limestone, which are found in the neighbourhood. A head of water of 200 feet is obtained from a waterfall in this stream ; the water is brought to the turbines by canals and iron conduits to the station, situated at 1,600 feet from the fall. Here are installed three turbines of 400 horse-power each, connected directly to a triphase alternator, working at 350 revolutions. The grinding machines will pulverise 8,000 Ibs. of lime and 5,000 lbs. of coke per day. This material is. transported , to an automatic balance, and thence by a con veyer to a screw mixing tank; from here it falls to the doors of the electric furnaces by a series of conduits. The mechanical operations are carried out by two electric motors. Nine double electric furnaces are used, with space for three others to be installed later; the furnaces have a capacity of 125 horse-power. The Meran works is one of the most