OF MICROSCOPIC OBJECTS. 83 



He then boils this until the albumen coagulates and the gelatine 

 is quite clear, when it is to be filtered through fine flannel, and to 

 each ounce of the clarified solution add 6 drachms of a mixture 

 composed one part of glycerine to two parts of camphor-water. 



GOADBY'S FLUID. This- is much used in the preservation of 

 animal objects ; and seldom, if ever, acts upon the colours. It is 

 thus prepared Bay-salt, 4 oz. ; alum, 2 oz. ; corrosive-sublimate, 

 4 grains. Dissolve these in two quarts of boiling water and filter. 

 For delicate preparations some recommend that this mixture be 

 reduced by the addition of an equal quantity of water ; but where 

 there is bone or shell in the object the above acts injuriously 

 upon it, in which case this fluid may be used : Bay-salt 8 oz., 

 corrosive sublimate 2 grains, water 1 quart. 



THWAITES'S LIQUID. This is recommended for the preservation 

 of Algae, &c., as having little or no action on the colour, and is 

 thus prepared : Take one part of rectified spirit, add drops of 

 creasote enough to saturate it ; to this add sixteen parts of dis- 

 tilled water and a little prepared chalk, and filter. When filtered, 

 mix with an equal quantity of camphor-water (as before men- 

 tioned), and strain through fine muslin before using. 



CHLORIDE OF ZINC SOLUTION. In the " Micrographic Dic- 

 tionary " this is stated to be " perhaps the best preservative known 

 for animal tissues." Persons of great experience, however, have 

 given a very different opinion ; but it is certainly very useful 

 in many cases where a small degree of coagulating action is not 

 injurious. It is used of strengths varying according to the soft- 

 ness of the parts to be preserved ; the average being 20 grains of 

 the fused chloride to 1 oz. of distilled water. To keep this liquid 

 a lump of camphor may be left floating in the bottle. I have 

 heard complaints that this mixture becomes turbid with keeping, 

 but I think this must only be the case when some impurity has 

 got into the bottle. 



CARBOLIC ACID. This substance has not been known long 

 enough to warrant any decided opinion upon its merits. A solu- 

 tion of 1 part of acid to 20 of water has been recommended on 

 account of its antiseptic properties. 



CASTOR OIL. This is a very useful preservative for crystals and 

 other objects. Many salts are quite destroyed when Canada bal- 



