254 CEMENTS AND VARNISHES. 



tained from the opticians or from J. Bell and Co., chemists, 

 338, Oxford Street, London. 



This varnish flows easily from the brush, and sets quickly. 

 For glycerin or other fluid mounts, the cover should be ringed 

 as above described with glycerin jelly before applying the 

 varnish. This precaution is especially necessary with glycerin. 

 This is the best varnish for fluid mounts known to me. It is 

 soluble in ether or chloroform. It is not attacked by oil of 

 cedar. 



435. Miller's Caoutchouc Cement. Composition unknown. 

 May be obtained from the opticians. A very tenacious and, 

 which is frequently an important point, a quickly drying 

 cement. 



436. Asphalt Varnish (Bitume de Jude'e). Unquestionably 

 one of the best of these media, either as a cement or a varnish 

 provided it be procured of good quality. It can be procured 

 from the opticians or from the oil-shops. KITTON (Month. Mic. 

 Joum., 1874, p. 34) recommends asphalt dissolved in benzol 

 with the addition of a small quantity of gold size. 



437. Brunswick Black. Best obtained from the opticians. 

 A receipt for preparing it is given in BEALE, How to Work, &c., 

 p. 49. 



' ' If a little solution of india rubber in mineral naphtha be 

 added to it, there is no danger of the cement cracking when 

 dry." Carpenter states that without this addition it is brittle 

 when dry. Brunswick black is soluble in oil of turpentine. 

 A most useful cement, works easily and dries quickly. It can 

 be recommended for turning cells. 



438. Brunswick Black and Gold Size (EULENSTEIN, BEALE, How 

 to Work, &c., p. 49). Equal parts of Brunswick black and 

 gold size with a very little Canada balsam. 



439. Gold Size. Receipts for preparing it may be found in 

 the Micrographic Diet, or in COOLEY'S Cyclopaedia ; but it is 

 certainly best to obtain it from the opticians or oil-shops. It 

 is soluble in oil of turpentine. A good cement, when of good 

 quality, and very useful for turning cells. 



440. Marine Glue. Found in commerce. Carpenter says 

 the best is that known as Gr K 4. 



It is soluble in ether, naphtha, or solution of potash. Its 



