(c) Ditto.—Take part of a newspaper, fold it small, dip it in a basin of clean cold water, and when it is thoroughly wet squeeze it out as a sponge, and then rub it hard over the face of the glass, taking care that it is not so wet as to run down in streams. After the glass has been well rubbed with the wet paper, let it rest a few minutes and then go over it with a fresh dry newspaper, till it looks clear and bright, which it will do almost immediately.
(d) Windows.—Procure a washleather of convenient size and some “paper-hanger’s” canvas; 2 yd. divided into 3 pieces, will be a nice size to work with. Have the cut sides hemmed, and they will last a long while. When it is desired, use one; boil or soak for an hour or so in a solution of soda and water to get out the “dress”; then wring out, and rinse in as many courses of clean water as you like; then partially dry (practice will enable you to judge), fold to a convenient size, and it will be ready for use. The soda solution will now be cool enough for the leather (if too hot it will shrivel the leather); wash in the same manner, and wring superfluous moisture out; then wash the glass thoroughly with it and plenty of elbow-grease, and polish off with the canvas.
(e) Ditto.—One of the best materials is a mixture of calcined magnesia with enough purified benzin to produce, when shaken up, a thick milk. It should be kept in vessels provided with well-ground glass stoppers. For use, a small quantity of the mixture is applied to a muslin rag, or better, to a wad of cotton, and the windows are rubbed with this. It may be very readily cleaned off without leaving any deposit in the corners.
(f) Glass Globes.—Rub inside with a little wet pumice-powder on a cloth, and in 2 minutes you would not know that they were not newly purchased. The best way to cleanse dirty glass of all kinds is to put a small quantity of spirits of salts (hydrochloric acid) into a basin of water, and to place the dirty articles in the liquid for a few minutes, when it will be found that the glass is clean, and only requires drying. If very dirty, the globes may require to stay in the liquid a little longer. This plan is very useful for cleaning the pendant drops of glass chandeliers, water bottles, &c., as no soap is required. Care must be taken not to drop the undiluted spirits of salts on the clothes or hands.
(g) Photographic Glass Plates.—One of the most powerful—if not, indeed the most powerful—detergents for refractory plates is the mixture of sulphuric acid and bichromate of potash recommended by Carey Lea some years ago. It is especially useful with glasses which have been frequently used, or which from the nature of the treatment they have undergone resist the action of both acids and alkalies completely. Its utility is dependent upon the powerful action of chromic acid upon organic matter, and we have never yet met with a plate which did not succumb to its treatment. One precaution is necessary in using it, however; it must be carefully removed from the glass by copious washing as soon as possible after it has done its duty. If allowed to soak for some time, as is frequently the practice, the plates appear to absorb the solution (the penetrating power of which is extraordinary), or an insoluble compound becomes firmly attached to the surface and stedfastly refuses to be displaced. Though generally invisible, it results in a peculiar mottled appearance between the glass and the developed film which entirely ruins the picture. We recently treated a number of plates which had become useless from this cause with various detergents, including acids as well as alkalies, but to no purpose; friction with various abrading powers failed to remove the defect, and we were well-nigh compelled to give it up. Remembering, however, that cyanide of potassium has been utilised by carbon printers for the purpose of reducing the strength of over-printed proofs—which it does by virtue of its action upon the insoluble compounds of chromium—we resolved to try its efficacy on our refractory plates, when all the mottling disappeared as if by magic. Those amongst our readers who dare to fly in face of all that has been lately written upon the dangers attending cyanide and bichromate of potash have here a “wrinkle.” Surely those who have dared bichromate will not fear the minor dangers of cyanide. (Brit. Jl. Phot.)
(h) Ditto.—A cream of tripoli powder and spirits of wine, with a little ammonia added, is a very good solution for cleaning glass plates. Old collodion is also very good; it should be thinned down with an equal bulk of spirits of wine; add an excess of iodide of potassium, and shake till the solution is saturated. Caustic potash is very good; so is carbonate of soda. If the plates be new, and covered with little gritty particles which do not come off on the application of potash, they may be removed with nitric acid.
(i) Ditto.—Take a dilute solution of potash permanganate, and pour on enough to wet the sides of the vessel to be cleaned. A film of hydrated manganic oxide is deposited, which is then rinsed with hydrochloric acid. Chlorine is formed, which acts in the nascent state on the organic matter, which becomes readily soluble. The permanganate solution can be used again and again till its oxidising power is exhausted. (Walz.)
(j) Ditto.—Dissolve 15 gr. potassium iodide in 5 oz. water and 5 oz. alcohol, afterwards adding 3 gr. iodine and enough whiting or rottenstone to make a creamy paste Rub a little of this on the glass with a rag until clean, then polish with a cloth. (J. Hughes.)
(k) Glass Slides.—“I had tried previously to remove the hardened balsam in many ways, and had succeeded fairly with a mixture of prepared chalk, methylated spirit, and liquid ammonia, but found this objectionable because it was such a dirty job. I now simply warm the slides over a flame, and push off the covers into strong sulphuric acid (oil of vitriol), and leave them therein for a short time; when clean, drain off, and rinse with a little fresh acid, and finish off by washing well in water. As much balsam as possible is removed from the slides by scraping with a knife, and then sulphuric acid is rubbed upon them with a glass rod. They are then well washed. If necessary, a finishing touch may be given with a warm solution of washing soda or methylated spirit and ammonia, to remove all trace of grease. Sulphuric acid should be added to water, or water to sulphuric acid, very gradually.” (Thos. H. Powell.)
(l) Removing Grease.—Dissolve soda carbonate in water, in the proportion of 1 of the former to 10 of the latter, and let the liquid boil in a clean untinned iron pot. Slake 8 parts quicklime in a covered vessel and add the hydrate thus formed to the boiling liquid, stirring it meanwhile. Great care must be exercised in using this caustic solution, which must not be allowed to touch the hands; the glass must therefore be dipped in it by the aid of tongs or pliers. When the grease is dissolved, the glass is to be well brushed and subsequently rinsed in water.