156 Royal Society. 



any thickness, from that of the finest tissue paper upwards. It may 

 be obtained as transparent as the best glass, and more free from colour, 

 or of all colours and shades of colour, without interfering with its 

 transparency. It is exceedingly light, and may be bent or rolled 

 up without injury. It can be cut with scissors like ordinary paper, 

 and may easily be stitched with a needle and thread. By means of 

 an aqueous solution of gelatine, it can be made to adhere accurately 

 to plates of glass without any interference with its transparency. 

 When varnished with collodion it becomes perfectly waterproof, more 

 pliable, capable of bearing a considerable degree of heat without 

 injury, and its transparency is not affected. 



Hence it appears, that, in addition to its transparency and suscep- 

 tibility to various colours and forms, gelatine paper is cheap, por- 

 table, and durable. 



Such being the properties of the material, the following are 

 enumerated by the author as some of the forms in which he suggests 

 that it may be employed, and in which it has already been found 

 useful. 



1. A small sheet of very pale green or blue gelatine paper, to 

 be used in reading. The sheet is simply to be laid upon the page 

 of the book, and the reading to be conducted through the coloured 

 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. 



2. A sheet of gelatine paper of pale green set in a light frame, 

 and placed like a screen before the window or lamp of the engraver, 

 the watchmaker, the jeweller, and the like ; thus providing a light 

 of genial colour in which they may pursue their occupations. 



3. A similar appliance to the last-mentioned for the use of 

 needlewomen. For this purpose screens are to be provided, both of 

 green and of blue gelatine paper ; so that the white materials em- 

 ployed in needlework may be changed to a pleasant green, by the 

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

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

 into violets or browns. 



4. For either of the two last purposes on a larger scale, the 

 gelatine paper may be attached to the window glass of the apart- 

 ment, thus colouring, if necessary, all the light admitted during day- 

 light. 



5. Shades for the eyes in certain affections of the sight, to take 

 the place of the green or blue silk and 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 pro- 

 tected from a glaring light. This may be especially useful in cases 

 where it is desired not only to shade a diseased eye, but also to pro- 

 tect its nerves from strong light admitted by the sound eye. When 

 not only coloured light but a certain degree of darkness is required, 

 this can be readily and delicately graduated by employing shades of 

 different depths of colour. 



6. Masks of gelatine paper for protecting the eyes of travellers 

 against the glare of snow-fields and of sandy deserts. 



