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664 THE PHOTOGRAPHIC NEWS. [OcTOBER 16, 1885. testing the standard solution. The number of cubic centi metres of solution required for neutralization gives the per centage of actual carbonate of soda. Or, by another method, any convenient quantity of the substance to be tested may be taken—say 70 grains, and let us suppose that 54 c. c. of acid are used. Then the following equation gives the per centage of actual carbonate. gr-equiv. °/ o carb, soda Grs. substance sod. carb. c.c. acid. in sample. 70 : 106 = 51 : 8177 Note.—It will be noticed that while using, mostly, the English weights and measures, in making and using the standard solution, the metric system of measurement has been made use of. The reason for doing this is that chemical apparatus is generally made for this system, and, when it is once understood that 1,000 cubic centimetres are equal to 1 litre, it will present no difficulty to anyone only acquainted with the English system. Jotes. “ Only for My Ears,” by F. Whaley—our supplement for this week—is a picture which tells its own tale, and, as a study of facial expression, should be valuable to an artist. Those visiting the Exhibition can see the original. The season of fogs is approaching, and photographers will soon find these unpleasant earth-clouds invading their studios. Under these circumstances it may be well to call attention to the discovery of Professor Lodge, who finds that a frictional electrical machine—the Wimshurst pattern for choice—provided with an abundance of “ points,” and vigorously worked, has the power of dispersing fog or smoke in an ordinary room, and of clearing the air in such a space in a very short time. The principle is being applied by lead smelters to the condensation of the ob noxious fumes, which at present they are compelled to condense in horizontal chimneys of immense length. Bicyclists who use the camera should turn to page 659, where they will find something to interest them. We have made a strut for our bicycle, and find that with the addition it makes a remarkably steady camera-stand. Reminiscences of the birth-time of photography are getting rarer, and should be cherished. The following is from H. Trueman Wood, Secretary of the Society of Arts. An uncle of mine told me the other day that he remem bers the English papers coming to Buenos Ayres with a note, giving an account of Daguerre’s discovery ; and the same paper had a paragraph to the effect that the rocks supporting the falls of Niagara had fallen. At his club a friend read out both these items. The Niagara account was put down as natural and to be expected, “ for how could any rocks withstand that enormous pressure of water;” but the statement to the effect that a Frenchman had invented a method of taking pictures without a brush or a pencil, was put down as one of the lies those news paper fellows are always inventing ! R. Kayser has found a cheap substitute for gum-arabic which may possibly be of use as a mount ant. By heating milk with a little tartaric acid, the casein is coagulated. This casein is then treated with a solution containing six parts of borax to one hundred of water, and warmed. It speedily dissolves, and forms a very tenacious, durable, and inexpensive adhesive medium. Would not ordinary skim cheese—such as Dutch cheese—dissolved in a solution of borax, answer the purpose as well ? Another tribute to the accuracy and usefulness of photo graphy comes from the British Association meeting at Aberdeen. In the Geological Section, Dr. B. II. Traquair described a new and very remarkable reptile, lately found in the Elgin sandstone, entirely from a photograph of the specimen submitted to him by Prof. J udd. He was able to assign the creature to the genus Dicynodon, which characterises similar sandstones in South Africa. From time to time doubts have been thrown upon the story of Daguerre’s accidental discovery of development by mercury. It will be remembered that he left one of his exposed plates in a cupboard containing a little loose mercury, and that an image was produced upon the plate by the condensation on its surface of the volatile metal. A recent note by the well-known French chemist Berthelot goes to support the truth of Daguerre’s story. In his laboratory a bottle of iodine stood at a distance of more than six feet from an open vessel containing mercury; yet a scarlet deposit of iodide of mercury was formed round the stopper of the iodine bottle. This proves not only that mercury evaporates at all temperatures (which was, indeed, previously well known), but that its vapour has great power of diffusion through the air. The Court Journal is of opinion that the photographer who goes in for making pictures of figure subjects has “ unwittingly created a new kind of art.” He requires, thinks our contemporary, “ the histrionic model,” one who is as capable as any actor of giving representation by his or her physiognomy of the various emotions the photo grapher wishes to portray. The painter, hitherto, has asked for models only for form, taking a something from each one gifted with superiority in any particular item. The expression, the painter claims to be able to evolve out of his own brain. The moral the Court Journal draws is, that artists may well learn from photographers in this particular, and seek for “ accomplished acting models.” The demand, it contends, will create the supply. There is certainly some force in these remarks. It is, however, somewhat singular that actors and actresses who, from the nature of their profession, should be exceptionally good models, often fail when taken in character. The artificiality is so apparent; the expression so forced. They are obviously acting. Is the wooden, puppet like look which too many have, due to the fact that actors require the footlights and the applause of an audience to give life to their feat ures 'I
