204 SELECTION AND USE 



it with success. Take gelatine, 1 ounce; honey, 5 ounces; 

 water, 5 ounces; rectified spirit, ounce; creosote, 6. drops. 

 Soak the gelatine in water until soft, and then add it to the 

 honey, which has been previously raised to a boiling heat in 

 another vessel. Then boil the mixture, and when it has cooled 

 somewhat add the creosote mixed with the spirit. Lastly, ni- 

 ter through fine flannel. When required for use, the bottle 

 containing the mixture must be slightly warmed, and a drop 

 placed on the preparation upon the glass slide, which should 

 also be warmed a little. Next, the glass cover, after having 

 been breathed upon, is to be laid on with the usual precau- 

 tions. The edges may be covered with a coating of Bruns- 

 wick black. Care must be taken that the surface of the 

 drop does 'not become dry before the application of the 

 glass cover; and the inclusion of air-bubbles must be carefully 

 avoided. 



ALCOHOL. Mixed with water in various proportions, alcohol 

 forms one of our best preservative liquids, for both animal and 

 vegetable substances. The chief objection to it is the difficulty 

 with which it is retained in the cell. 



THWAITE'S FLUID. Take water, 16 ounces; alcohol, 1 ounce; 

 creosote, sufficient to saturate the spirit; chalk, as much as may 

 be necessary. Mix the creosote and spirit, stir in the chalk 

 with the aid of a pestle and 'mortar, and let the water be added 

 gradually. Next add an equal quantity of water saturated with 

 camphor. Allow the mixture to stand for a few days and filter. 

 Used for preserving desmidise, and also animal substances. 



BEALE'S LIQUID. Creosote, 3 drachms; wood naphtha, 6 

 ounces; distilled water, 64 ounces; chalk, as much as necessary. 

 Mix the naphtha and creosote, then add as much prepared 

 chalk as may be sufficient to form a thick, smooth paste; after- 

 wards add, very gradually, a small quantity of the water, which 

 must be well mixed with the otjer ingredients in a mortar. 

 Add two or three small lumps of camphor, and allow the mix- 

 ture to stand in a lightly covered vessel for a fortnight or three 

 weeks with occasional stirring. The almost clear supernatant 

 fluid may then be poured off and filtered if necessary. It should 

 be kept in well-corked or stoppered bottles. 



