186 Modern Microscopy 



section comes away from the glass, then wash well in clean 

 water. 



(8) Make a cell with black shellac cement and allow 

 it to dry; then apply another coat of cement, and after 

 waiting a few minutes fill the cell with camphor water, and 

 put the section into it ; apply a cover-glass, and press it 

 down until it adheres to the cement all round. Sections 

 of teeth are made in the same way. 



Rock Sections. — Small pieces or slices of rock are to be 

 ground on a zinc plate with the aid of emery-powder and 

 water until one side is quite flat and smooth. Then fasten 

 the polished surface to a square of glass with some dried 

 Canada balsam, as directed for bone, and allow it to cool. 

 Grind the other side on the zinc plate with coarse emery 

 and plenty of water. When moderately thin, take a piece 

 of plate-glass and some fine flour-emery, and rub the 

 section down as thinly as possible. When thin enough, 

 wash well in water and dry ; then warm over a spirit-lamp, 

 and with a needle push the section off the glass into a 

 saucer of benzole or turpentine, and allow it to soak until 

 all the balsam is dissolved. Wash again in some clean 

 benzole, and mount in Canada balsam in the usual way. 

 Sections of echinus spines, shells, and stones of fruit are 

 prepared in the same way as bones and teeth ; but when 

 the grinding is finished, the sections are to be passed through 

 alcohol into clove-oil, then mount in Canada balsam in the 

 usual way. 



Sections of coal containing fossils, limestone, spines of 

 echinus, and other friable specimens should be cut with a 

 very fine saw, and then soaked in benzole for several hours. 

 When the benzole has saturated the tissue, transfer to ordi- 

 nary solution of Canada balsam in benzole, and soak again 

 until the balsam has penetrated to the centre. Take a 3 x 1 

 inch slide, place the section on its centre, and add sufficient 

 balsam to cover it. Put away out of reach of dugt until 

 the benzole has evaporated from the balsam. Then place 

 on a hot plate, apply gentle heat with a spirit-lamp, and 



