126 THE MICROSCOPE. 



structures, Foraminifera, &c., may be thus treated; 

 the oil of turpentine entering into the cavities or 

 tissues, excludes the air. 



Spirit and distilled water form an excellent medium 

 for preserving animal tissu'es; one part of alcohol, 

 60 over proof, to five parts of distilled water, will 

 t>e found of sufficient strength for preserving many 

 substances. Methylated alcohol, which pays no duty, 

 answers very well, and it may be obtained at the 

 price of five shillings and sixpence per gallon. A drop 

 of this dilute alcohol is to be placed, by means of a 

 glass rod, on the glass slide, the tissue is to be sunk 

 into it, and covered with thin glass ; care must be 

 taken to exclude air-bubbles, the superfluous fluid 

 drained off, and the edge of the glass cover and ad- 

 jacent portion of the slide wiped quite dry. A ring 

 of cement gold size may be especially recommended 

 is to be laid round the edge of the thin glass, so as 

 to fix the cover on the slide. After this coating has 

 hardened, apply a second and a third. 



A solution ot glycerine with camphor-water is another 

 valuable fluid for preserving structures. Price's gly- 

 cerine is superior to any other for microscopic pur- 

 poses. The proportion of glycerine and camphor- 

 water will depend on the nature of the object to be 

 mounted ; for general purposes, one part of glycerine 

 to two parts of camphor-water will be found useful. 

 There are various other preservative fluids and cements 

 which are very useful in microscopic work, but those 

 I have named will be sufficient for most practical 

 purposes. 



Test-liquids are of immense use to the microscopist ; 

 they are employed to remove certain substances which 

 he wishes to get rid of, or to detect the presence of 

 particular substances in the object under examination. 

 For instance, suppose I wish to obtain the animal 



