262 ANNUAL OF SCIENTIFIC DISCOVERY. 



tificial flowers, address cards, tracing paper, wafers, etc. It is commonly 

 manufactured in sheets, measuring 22 inches in length by 16 in breadth, 

 which are sold at a small price ; but sheets can be easily made of any dimen- 

 sions not exceeding those of which plate-glass is capable. It can also be 

 made of any thickness from the finest tissue upward. It may be obtained as 

 transparent as the best glass, and more free from color, or of all colors and 

 shades, without interfering with its transparency. It is exceedingly light, and 

 may be bent or rolled up without injury. It can be cut with the scissors 

 like ordinary paper, and may be easily stitched with a needle and thread. 

 By means of an aqueous solution of gelatine, it can be made to adhere accu- 

 rately to plates of glass, without any interference with its transparency. 

 When varnished with collodion, it becomes perfectly water-proof, more pliable, 

 capable of bearing a considerable degree of heat without injury, and its trans- 

 parency is not affected. Hence it appears that gelatine paper, in addition to 

 its transparency and susceptibility to various colors and forms, is cheap, port- 

 able, and durable. Such being the properties of the material, Mr. Dobell 

 suggests its employment for various purposes, and especially for preserving 

 and benefiting the sight, for which it maybe used as follows : A small sheet 

 'of very pale green or blue gelatine paper may be used in reading. The sheet 

 is simply to be laid upon the page of the book, and the light conducted 

 through the colored medium. If used in a faint light, the reading paper is 

 to be raised a little from the book to admit more light beneath it. A sheet 

 of gelatine paper may be set in a light frame, and placed like a screen before 

 the window, or lamp of the engraver, the watchmaker, etc. ; thus providing a 

 light of genial color in which they may pursue their occupations. Similar 

 appliances may also be used by needle-women. For this purpose screens are 

 to be provided, both of green and blue gelatine paper ; so that the white 

 materials employed in needle-work may be changed to a pleasant green, by 

 the screen of that color, the yellow materials to a green by a blue screen, 

 and by one or the other of these screens the reds softened down into 

 violets or browns. For either of the two last purposes on a larger scale, 

 the gelatine paper may be attached to the window-glass of the apartment, 

 thus coloring, if necessary, all the light admitted during daylight. Shades 

 for the eyes, in certain affections of the sight, may be made of gelatine paper, 

 to take the place of the green or the blue silk, or card shades, worn by many 

 persons. The gelatine paper, being transparent, will allow the wearer to see 

 his way about, at the same time that the eyes are protected from glaring 

 light. This may be especially useful in cases where it is desired not only 

 to shade a diseased eye, but also to protect its nerves from strong light 

 admitted by the sound eye. Masks of gelatine paper may also be used for 

 protecting the eyes of travelers against the glare of snow-fields and of sandy 

 deserts. Lon. Edin. and Dub. Phil. Journal. 



ON THE PREPARATION OF ROUGE AS A POLISHING POWDER. 



To get the employment of oxyd of iron obtained by the calcination of 

 protoxalate of iron in preference to the lixiviated colcothar as a polishing 



