[39] 



Zbc HDicroscopc an^ bow to use 



By V. A. Latham, F.R.M.S. 



Part XIII. — Cements and Useful Recipes. 



THE chief cements in microscopical work are gold-size, seal- 

 ing-wax varnish, solution of shellac, solution of asphalt, 

 marine glue, and Canada balsam. 



Gold-Size. — Prepared by melting together gum animi, boiled in 

 linseed oil, red lead, litharge, sulphate of zinc, and turpentine. 

 Take 25 parts of linseed oil, boil with one part of red lead, and a 

 third part as much umber, for three hours. The clear fluid is 

 poured off and mixed with equal parts of white lead and yellow 

 ochre, which have been previously well pounded. This is to be 

 added in small successive portions and well mixed. The whole is 

 then again to be well boiled, and the clear fluid poured off for use. 

 The o/der the cement the better it is. This cement may be 

 bought ready for use. 



Sealing-Wax. — Prepare by dissolving the very best powdered 

 sealing-wax in fairly strong alcohol with a gentle heat. It is apt 

 to dry rather brittle, but forms a good varnish for the last coat. 



Shellac is made by dissolving powdered shellac in spirit of 

 wine. Shake the bottle frequently until a thick solution is 

 obtained. 



Bell's Cement. — I believe this was originally suggested by Mr. 

 Tomes. It is sold by Messrs. Bell, chemists, Oxford Street. I 

 do not know the composition, but think it contains shellac and 

 gold-size. 



Brunswick Black.— -Take of india-rubber, cut into very small 

 pieces, i drachm; asphaltum, 4 oz. ; Mineral Naphtha, 10 oz. 

 Dissolve the india-rubber in the naphtha, then add the asphaltum ; 

 if necessary, heat must be employed. Some friends say they 

 cannot always succeed with this. I believe the faults are — either 

 the rubber or asphaltum has not been pure^ or that the naphtha 

 used has been wood instead of mineral. 



Common Brunswick Black is made by melting one pound of 

 asphaltum ; then adding half a pound of linseed oil and a quart 



