ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 309 



is then made in tlie usual manner, and the cover-glass dried in the air 

 and fixed in the flame. 



Glycerin Mounts.* — G. H. C. says that for this purpose it is best to 

 use a cell made of hard rubber, unless the object be very thin, in which 

 case cement cells may answer, but they should be at least two or three 

 weeks old, otherwise the cement in drying may shrink, so that the cell 

 becomes too small to contain all the glycerin, part of which may thus 

 be forced out and rupture the mount. Clean the cover, and having 

 centered the slide on the turntable run a ring of fresh cement tolerably 

 thick around the top of the cell, and as quickly as possible put in the 

 glycerin, about a drop more than enough to fill the cell up level. Eun 

 a needle around inside the cell to draw the glycerin quite up to the 

 cement all round but not on to it, otherwise you may have trouble with 

 bubbles. Put in the object and arrange it as quickly as possible. Take 

 the cover between the thumb and the forefinger, wipe the cement, brush 

 so that there is no excess of cement on it, and draw a ring of about 

 1/16 in. wide round the cover. Take it in the tweezers at the place 

 where the cement is widest, not letting the points extend any further 

 into the ring of cement than is unavoidable, breathe on the cover, invert 

 it over the cell, and press down all round with a needle-handle. Einse 

 off the excess of glycerin with clear water and dry with blotting-paper. 

 You may ring round afterwards or not as you please, but if you have 

 been quick enough not to give the cement time to dry they will be 

 tight and permanent. 



Beck, J. D. — A beautiful and durable Cement for ringing Balsam Mounts, 



[" To a thick solution of gum arabic add a little glycerin to prevent cracking. 

 Ring balsam mounts with this first, then finish with the cement coloured 

 with magenta, or fuchsin, or the ' Diamond ' black dye dissolved in water. 

 Ornament with gold paint, &c., and finish with Winsor and Newton's mastic 

 picture varnish. Try cement on a blank slide ; if brittle when hard, add 

 a little more glycerin, so that it will harden in twenty-four hours without 

 brittleness."] 



The Microscope, IX. (1889) p. 18. 

 Benedikt und Ehrlich. — Zur Kenntniss des Schellacks. (On shellac.) 



SB. K. Akad. Wiss. Wien, XCVII. (1888) p. 127. 

 Cement (" inside ") for Balsam Mounts. 



[(1) Clear shellac cement, or colourless marine glue. (2) Seiler's gelatin 

 cement.] 



Queen's Micr. Bulletin, V. (1888) p. 45. 

 Dry Mounts. Ibid., p. 25. 



C6) Miscellaneous. 



Practical Utility of the Microscope to Textile Workers.f — A ques- 

 tion arising as to whether a large lot of yarn delivered at a mill equalled 

 in quality the sample lot on which the order was based, tests were made 

 as follows : — In lot No. 1, fifty fibres averaged under the Microscope 

 1/1265 in. in diameter. In lot 2, fifty fibres averaged 1/1260 in. in 

 diameter. Of lot 1, thirty-six fibres, and of lot 2, thirty-five fibres, 

 ranged in diameter between and including 1/1500 and 1/1200 in., show- 

 ing a most remarkably close approach in quality of a large delivery to 

 the sample order. 



Sixteen loose outside fibres from a two-ply No. 40 worsted yarn, 



* Queen's Micr. Bulletin, v. (1888) p. 42. 

 t T. c, p. 19. 



