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THE PHOTOGRAPHIC NEWS. Vol. XXIX. No. 1396.—June 5, 1885. CONTENTS. PAGE Notes 360 Patent Intelligence Meteorology for Photographers. By J. Vincent Elsden, B.B.G. (Lond.). 36l Trip with the Camera into Hampshire. By Charles Allan Ferneley 362 The Cruise of the Ceylon, 1885. By Norman May 363 Correspondence 365 Proceedings of Societies 366 Talk in the Studio 367 Answers to Correspondents 368 PAGE Phenyl-Hydrazine : A New Developer. By Dr. J. Maria Eder 353 Surveying by the Aid of Photography ................................ o 3 Further Remarks on Sulphite of Soda. By Captain W. de W . Abney, R.E., F.R.S ••••••• 3>4 The Behaviour of the Haloid Salts of Silver in the Solar Spectrum, and the Exaltation of their Sensitiveness towards Certain Parts of the Spectrum. By Dr. Eder... 355 Artistic Feeling in Photography. By A. II. Wall 357 A Few Fallacies •.••• 358 A Rocking Stand for the Developing Bish 359 An Electrical Standard for Measuring Light 359 SURVEYING BY THE AID OF PHOTOGRAPHY . 11 .• , , ‘ " camerd is very UVISIMOIONIY Mo-W VJ - •1 —NA with caustic potash is a very powerful developer for means of assisting them in the production of drawings cola+inA-chloride anA vxy IV c1+; nA chlorA. . 1 c 1 . Dr. Vogel has, after consultation with his friend Herr Professor Doergens, solved the problem in an exceedingly The appliances marked g h i are the only additions ised. After this it is filtered, heated to boiling, and one- The hydrochlorate of hydrazine now separates in crystals. Continued from page 322. So far we have treated of photogrammetry as applied to land surveying only—to the production, that is to say, .2 c. There is another application of it, however, which is possibly more extensive and more likely to be useful than this one of map making. It is that of archi tectural surveying ; that of making plans and elevations of buildings. In a recent number of a German photo graphic contemporary, Dr. Vogel has a very comprehen sive article on the application necessary for the perform ance of surveys of this kind. From this we learn that the I camera is very considerably used by German architects as One cannot at the present moment form an opinion as to whether the new developer possesses any practical value, but I will give a few details as to chemical consti- should be designed for photogrammetrical purposes. It is necessary in such a case to have a means of determining the horizon line, and where possible also the point of view (Augenpunkt). Meydenbauer accomplishes this by means of fixed marks, against which the plate in the camera rests, and he makes use of a peculiarly-constructed camera. The problem was to reach the same end with the usual appa ratus and an ordinary dark slide. of buildings. Already a considerable number of architects make use of photography in their surveying, and it there fore became desirable that a well-constructed camera tution and preparation of the hydrazines. The hydrazines contain the’group N,H, or NII—NH, Fig.1. the arrangement readily intelligible. B B represent the bellows of an ordinary camera of substantial and exact i construction. A is a single dark slide working in the I usual grooves, C C. So far the camera is the same as any gelatino- chloride, and for Wellington’s gelatino-chloro- bromide ; there being no tendency to fog. On silver bromide its action is less energetic. The colour of the image obtained is generally yellowish brown, but under other conditionsit is greyish black. The phenyl-hydrazine developer remains colourless for a long time, but in the end it becomes yellowish, and ac quires the smell of tar products. PHENYL-HYDRAZINE: A NEW DEVELOPER. | BY DR. J. MARIA EDER. The hydrazines possess powerfully reducing properties, arid reduce in the cold solutions of silver, gold, platinum, and mercury salts: even alkaline copper solution is reduced. I have made experiments specially with the hydro chlorate of phenyl-hydrazine, the compound having been . obtained through Dr. Walter, of Basle. This salt forms P LlLPis white crystalline leaflets, which are permanent in the air, "" 5 easily soluble in alcohol, and sparingly soluble in water. The aqueous solution reduces silver nitrate, but not silver bromide or chloride. a...... . .Jg, auucuc necessary for photogrammetrical purposes, and they third of its volume of strong hydrochloric acid is added. \ almost explain themselves ; g g are two circular rods If the hydrochlorate of phenyl-hydrazine is mixed with an alkali, the base (hydrazine) is set at liberty, and this base is, to some extent, soluble in water. The mixture. Phenyl hydrazine has the composition CsH,—NH—NH„ and the hydrochlorate contains C,H,— N,H- HC1. water bath, and when the greater part of the separated, . . salt has dissolved, the liquor is neutralised with hydro- other, except in as much, as great precision is, of course, chloric acid. It is next acidified with acetic acid, andnecessary in .construction.. , . . while warm is treated with zinc dust until it is decolour- V • * , - . . A IVI---V1 ••-*8-) •V-K PNII XIX ~ A--MS 1J and they are formed (a) by the reduction of nitrosoamines I ingenious manner. with zinc and acetic acid ; () by the reduction of diazo 1 ‘The accompanying cuts will render an explanation of compounds with sodium sulphite; (c) by reduction of diazo-amido compounds with zinc and acetic acid. | The hydrochlorate of phenyl-hydrazine is prepared as 1 follows -.—Twenty parts of aniline are dissolved in 50 parts ) of hydrochloric acid (s. g., 1-19) and 80 parts of water ; this solution being then treated in the cold with the calcu lated quantity of sodium nitrite (this salt being dissolved | in double its weight of water, and slightly acidulated with I hydrochloric acid). The mixed solution is now slowly | poured into excess of an ice-cold and saturated solution of sodium sulphite, and as soon as a sample of the crystals i which separate redissolve in the mother liquor without evolving gas on the application of heat, the next stage is reached. The whole is now heated cautiously on the