246 PEESERVATIVE LIQUIDS. 



cerin. This, and the following glycerin jellies, must of course 

 be used warm. 



407. Lawrence's Glycerin Jelly (DAVIES, Preparation and 

 Mounting of Microscopic Objects, p. 84). "He takes a quan- 

 tity of Nelson's gelatin, soaks it for two or three hours in cold 

 water, pours off the superfluous water, and heats the soaked 

 gelatin until melted. To each fluid ounce of the gelatin, 

 whilst it is fluid but cool, he adds a fluid drachm of the white 

 of an egg. He then boils this until the albumen coagulates 

 and the gelatin is quite clear, when it is to be filtered through 

 fine flannel, and to each ounce of the clarified solution add 

 6 drachms of a mixture composed of 1 part of glycerin to 2 

 parts of camphor water." 



408. Scale's Glycerin Jelly (How to Work, &c., p. 57). 

 Gelatin or isinglass, soaked, melted, and clarified if desired, 

 as in the last formula. To the clear solution add an equal 

 bulk of strong glycerin. 



409. Brandt's Glycerin Jelly (Zeit.f. Mik., ii, 1880, p. 69; 

 Journ. Roy. Mic. Soc., iii, 1880, p. 502). Melted gelatin 1 

 part, glycerin 1J parts. 



The gelatin to be soaked in water and melted in the usual 

 way. After incorporating the glycerin, the mixture is to be 

 filtered. This is a point of vital importance, as the gelatin of 

 commerce is always mixed with particles of dust and minute 

 threads. Swedish filtering-paper does not allow the fluid to 

 pass through sufficiently, and flannel produces more threads 

 than before. The following simple apparatus is found effec- 

 tive. A wide-necked bottle is broken in two, and the upper 

 part taken. The neck is stopped with a cork having two holes 

 bored in it. In the first hole a glass tube, about 20 cm. long, 

 is inserted so as to project a little into the inside of the bottle, 

 and on the outside it is bent sharply to one side and drawn 

 out into a point of about 1J to 2 mm. diameter. In the 

 second hole a funnel-shaped filter is inserted so that the coni- 

 cal part is inside the bottle and the tube projects a few centi- 

 metres beyond the cork and the neck of the bottle. The 

 apparatus is then placed so that the wide opening of the 

 bottle and of the funnel is uppermost, and some spun glass 

 is pressed into the lower conical part of the filter. In using 



