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736 THE PHOTOGRAPHIC NEWS. [NOvENIBER 16, 1883. precisely the reverse of that which would be produced by the latter, were the ray of light merely a source of heat. Secondly, actino-electricity reaches its maximum about 40" after the commencement of the radiation, and disappears at about the same interval of time after the withdrawal of the radiating body ; whilst the pyro electric difference of potential is slowly evolved by heating or cooling the crystal. Thirdly, it is proved that the actino-electricity is not produced by unequal heating of the crystal. But if the radiation be long continued, then from the warming of the mass of the crystal, pyro-electricity is produced, causing ultimately an opposite polarity in the axes. Experi ments are also quoted to show that actino-electricity is a reversible phenomenon, for the approach of a cold body near a crystal causes an opposite polarity to that produced by a warm body. —Journal of the Chemical Society. Bromine in the United States.—According to a paper read before the American Pharmaceutical Association, the annual production of bromine in the United States amounts to from 450,000 to 500,000 lbs. It is obtained from the bittern of salt wells—i.e., the residue after the salt has been removed from the brine—and in six localities named, the bittern is so rich, that, for every two barrels of salt it yields one pound of bromine. The separation of bromine is said to be now carried on at all the brine works where it can be conducted profitably, and unless fresh deposits are discovered, the production is more likely to decrease than increase.—Journal of the Society of Arts. Photographic Club.—At the next meeting on Wednesday, November 21st, the subject for discussion will be “Alkaline Pyro. Development, relative merits of different formula;, and methods of employing them, especially with the object of developing rapid exposures.” G0 *,* To HoN. Secretaries of Photographic Societies.— Kindly send in at once to the Editor of the Year-Book of Photography, care of Messrs. Piper and Carter, 5, Castle Street, Holborn, a revised list of president and officers, together with place and day of meeting. August.—You will find the Dallmeyer lens you mention will do all you state. T. S.—If you will look in our advertising columns, you will see that Mr. Cowan’s plates are in the market. Engraver.—1. It is certainly better to usepcrchloride of iron than nitric acid, under such circumstances as you refer to. 2. The coating of nickel is so thin as in no way to interfere with the clearness and definition of the work, but it forms a very effectual protection against wear. Calx.—Although perfectly pure, sugar contains no mineral or in organic matter; you are likely to have some difficulty in obtain ing a sample which will leave no trace of ash when burned. Dry Plate.—1. Place the beaker which contains the emulsion in a large vessel containing warm water, and add a little boiling water from time to time. 2. They are generally made by machinery, but occasionally by hand. M. E.—You may regard ordinary whiting as the basis of the pigment, and the required modifications in tint are attained by the use of vegetable black, ochre, or umber; these colours should, with the exception of the whiting, be purchased already ground with water; and for use they are mixed with a warm ten per cent, solution of glue. The proportion of pigment to be added must be determined by experiment—a friable coating indicating too much pigment, while a semi-lustrous appear ance of the dry distemper shows that the glue is in excess. A. H. Short.—Perhaps Messrs. Marion and Co., of Soho Square, could obtain it for you. II. S.—1. Either a portable symmetrical lens or a wide angle rec tilinear will be best for the purpose, and your camera should be provided with a rising front. 2. We do not know where you could see it in action, as naturally those who uss it commercially would scarcely care about devoting much time to demonstrating its action to those who might perhaps become rivals in trade. 3. The pictures are very pleasing, and we congratulate you on having secured easy and natural poses. Bristolian.—Do not blame the formula, but look well to camera slides, shutters, and dark room blind, as we are of opinion that you will find that the mischief arises from the action of light on the plate. Little Photographer.—The difficulty of judging as to the density is considerably greater than in the case of a collodion nega tive, and we can only suggest that you should select some dozen characteristic negatives, attach a print to each, and look over the series occasionally. An Anxious Enquirer.—You can obtain it from the Artists’ Colour Manufacturing Co., 31, Hatton Wall, E.C. Robert B .—No copyright can ever exist in the original after its publication in the manner you describe ; but you can establish some kind of a “Bogus” copyright by working up one of the original copie?, reproducing it, and registering as a fresh picture. GlassHouse.—We would strongly advise you to take no steps, or you may find that your own position will be altogether under mined. Copper.—It is due to the formation of a thin layer of subchloride ; bnt this can be cleared oft’at once by immersion in dilute hydro chloric acid. John Handson.—1. It is a case of the reversed action of light. 2. A practical article on the subject will be found in the forth coming Year-Book, which appears on the 20th of next month. 3. See a paper by Mr. C. Cuttriss, on p. 321 of our volume for 1881. 4. Plain collodion is an excellent varnish for the purpose. 5. We are not surprised at it, as we should have acted in exactly the same way. 6. Mr. Spiller’s astringent solution is composed of— Alum ... 1 ounce Citric acid | ounce Strong ammonia | ounce Water 16 ounces L. B. B.—Immediately after the image has been transferred to stone, and all trace of the paper or facing have been removed, the surface is brushed over with mucilage of gum-arabic, and when this is dry you may safely transmit the stone to a lithographic printer. 2. Full information will be found in Richmond’s “Grammar of Lithography, ” published by Wyman, of Great Queen Street, London. Ule 2qotographic Lews Zegistrg. Employment Wanted. Retoucher and Colourist —L. T., 28, Sherlock-rd., Mansfield-rd., N.W. Reception Room,. Spot, &c.—E. 8., Cambridge House, Amhurst-park, N. Operator and Retoucher.— G., 6, Ann-st., Tettcnhall-rd., Wolverhampton, Printer and Toner, or Assist. Operator.—A. Z., 151, Sandringham-rd., N. Optical.—Manager or Principal Assist.—Optic, Photographic News Office. Collotype, Photo-litho, &c , Operator.—Photo-mechanical, Photo. News. Operator, lighting & posing.—F. W. C., 8, Bolton-rd.. 11 igh-rd., Chiswick Operator, clever with children.—A. P., Photographic News Office. Printer, Toner, 4c., first-class.—A. Z.. 151, Sandringham-rd., Dalston: Operator and Retoucher.— H.C.S., 4, Beatrice-villas, Ossory-rd., S.E. Finishing Enlargements at Home.—L. K., Spring House, Merton, Surrey. Recep. Room.—Colouring, & Spotting (Lady).—H., 36, Pulford-st.,Pimlico. Assist. Printer and Toner.—H. Adams, 7, Albert-ter., Sandown, I. of W. Landscape Photographer.— Operator, Aslett House, Sandown, 1. of W. Employment Offered. Artist (first-class) for Calcutta.—T. E. A., 19, Wigmore-st., Cavendish-sq. Youth, to Sensitize Paper.—T. J. Turner, 10, Barnsbury, N. Retoucher (Lady) for permanency.—Turner and Killick, 17, Upper-st., N. Photo-Lithographer, used to Woodbury type.—Z.V., 150, Queen Vic.-st., E.C. Silver Printer, also Assist.—Boning and Small, 22, Baker-st., Portman-sq- Operator and Retoucher.— D. and G., 158, Regent-st., W. Printer & Toner, good Vignetter (perm.).—Acetate, Photo. News Office. Assistants, A. G. B. Enlarging Department.—Morgan & Kidd, Richmond* Retoucher, also Lady to Spot.—A., Photcgraphic News Office. Silver Printer and Vignetter.—Cox, Tavistock Chambers, Nottingham. Young Man, generally useful.—A. B. C., Mr. Richarison. High-rd., Lee. Gelatine Plate Coater.—X. X., Rouch and Co., 180, Strand, W.C. Operator, first-class.— Debenham and Gabell, 158, Regent-st., W. Young Lady, Reception Room.—II. R., Photographic News Office. Silver Printer and Toner.—R. Steward, Elgin. Manager of Photo, and Optical Business.—B.B., P.O. Vigo-st., W. Artist, Club Work in Oil.—W. II. Ledgard, 11, Lumb-lane, Bradford. A QUARTER OF A CENTURY OF PUBLICATION. The simple fact that the Tear-gook of photogrugu has run out of print during the past two years within six months of its publication, is proof sufficient of its popularity and wide circulation, and Messrs. PrPER and CARTER, in announcing its appearance for 1884, need put forward no better claim as to its value as an adver tising medium. Intending Advertisers in the AYeur-Zooh of Pvt- graphy and hotograpkic 3cws AImac should com municate with them at once at the Office, 5, Cash < STREET, HOLBORN, London, E.C.