160 



DESCRIPTION OF AlV EYE BATH. 



It is sufficiently singular, that the same 

 substance which is so useful in giving 

 sensibility to the paper, should also be 

 capable, under other circumstances, of 

 destroying it ; but such is nevertheless 

 the fact. Now, if the picture which has 

 been thus washed and dried, is placed in 

 the sun, the white parts color themselves 

 of a pale lilac tint ; after which they be- 

 come insensible. Numerous experiments 

 have shown the author that the depth of 

 this lilac tint varies accordinj^ to the 

 quantity of salt used, relatively to the 

 quantity of silver, but by adjusting these, 

 the images may, if desired, be retained of 

 an absolute whiteness. He mentions, 

 also, that those preserved by iodine are 

 always of a very pale primrose yellow, 

 which has the extraoidinary and very 

 remarkable property of turning to a full 

 gaudy yellow, whenever it is exposed to 

 the heat of a fire; and recovering its 

 former color again when it is cold. 



Brit. Jissoc. Atheneum. 



FILES AND RASPS MADE FROM CLAY. 



Files and other instruments for the 

 abrasion of various substances may be 

 made by folding up separate pieces of 

 wet clay, in muslin, cambric, and Irish 

 linen, forcing them by the pressure of 

 the hand into the intersticesof the threads, 

 so that on divesting them of the covering 



* From the success of this experiment we should 

 suppose that clay might be burned hard enough to 

 separate clover seed from its chaff, and in some cases 

 used advantageously for grinding grain. The little 

 expense required in forming and burning them would 

 enable the proprietor to renew them when necessary, 

 without inconvenience. Each pi'ce might be made 

 one or two inches thick and have both sides formed 

 into furrows similar to a mill stone and be confined 

 to the face of a block of stone or wood by bolts, screws 

 and nuts, so that when one side becomes too smooth 

 to operate well, the sides might be reversed ; or the 



and having them well baked a file, ia pro- 

 duced of a new species, said to be capable 

 of operating on steel ; and very useful 

 in cutting glass, polishing, and rasping 

 wood, ivory, and all sorts of metals. 



DESCRIPTION OF AN EYE BATH. 



This apparatus consists of a stand or 

 pedestal supporting a glass vessel, of 

 either a globular or any other proper 

 form. This last has a neck at the lower 

 end, and an aperture at the top to fit the 

 eye. The neck is cemented into a brass 

 tube, screwed into an ornamental piece 

 of brass work, in the upper part of the 

 pedestal. This tube contains a common 

 pewter syringe, the end of which is ce- 

 mented into the neck of the glass vessel. 

 When the instrument is used, the glass 

 vessel is to be partly filled with water 

 (or any othef liquid with which th,e eye 

 is- to be syringed,) so as to cover, the 

 orifice of the syringe; the patient then 

 places his eye over the aperture in the 

 glass vessel, and suddenly lifts up the 

 brass slider, to which the handle of the 

 syringe is fixed, so as to force the liquor 

 contained in the syringe through that in 

 the glass vessel into the eye ; the liquor 

 which covers the point of the syringe 

 takes ofl:' the force with which the liquor 

 would be thrown into the eye, so as to ren- 

 der the operation not in the least painful. 



furrows might be made upon the edges of each piece> 

 and the whole of them (sufficient to form a complete 

 rubber,) bound together by two iron hoops bound 

 upon them while hot, in the manner that French bur 

 mill stone blocks are confined together. Or each hoop 

 might be formed of two semicircles, with a flanch at 

 each end, so formed that the two pieces might be 

 drawn with sufficient force around the pieces of burned 

 clay by a screw bolt. The edges of each piece might 

 then be alike and each in turn made a rubbing surface 

 by removing the screw bolts, and again attaching them 

 after the pieces were changed and properly adjusted. 



CONTENTS OF NO. 10. VOL. I. OF OBSERVER AND RECORD, 



Conserve of Grape, 145 



Liquid Sugar fronv Apples and Pears. . . . 145 

 Hints on various Modes of Printing from Auto- 

 graphs, 147 



A Spring Crutch, 147 



Mr John Kent's Patent of a new and expeditious 

 Method of moving all kinds of Goods or Ma- 

 terials from high Buildings or deep Places, . 148 

 Method of preparing Ox-gall in a concentrated 



state, for the use of Paintersand other Persons, 148 



On Raising and Planting Apple Trees, . . . 148 



Observations on Fermentation, 149 



Sir H. Davy's Agricultural Chemistry, . . . 149 



Preparation of Indigo, 153 



Wind Mill (on Mechanics,) . 154 



Definition of Terms. Letter H., 155 



Photogenic Drawing, . . 158 



Files and Hasps made from Clay, 160 



Description of an Eye Bath, 160 



