228 THE MICROSCOPE. 



For No. 2 solution, bay salt, 4 oz. ; alum, 2 oz. ; corrosivft 

 sublimate, 4 grs. ; boiling-water, 2 quarts : mix. 



The No. 1 is too strong for most purposes, and should 

 only be employed where great astringency is needed to 

 give form and support to very delicate structures. No. 2 

 is best adapted for permanent preparation ; but neither 

 should be used in the preservation of animals containing 

 carbonate of lime (all the mollusca), as the alum becomes 

 decomposed, sulphate of lime is precipitated, and the pre- 

 paration spoiled. For such use the following : — 



Bay salt, 8 oz. ; corrosive sublimate, 2 grs.; water^ 

 1 quart : mix. 



The corrosive sublimate is used to prevent the growth 

 of vegetation in the fluid ; but as this salt possesses the 

 property of coagulating albumen, these solutions cannot be 

 used in the preservation of ova, or when it is desired to 

 maintain the transparency of certain tissues, such as the 

 cellular tissue, the white corpuscles of the blood, &c. 



Mr. Goadby's method of making marine-glue for cement- 

 ing cells is as follows : dissolve separately equal parts of 

 sliell-lac and India-rubber in coal or mineral naphtha, and 

 afterwards mix the solutions carefully by the application 

 of heat. It may be rendered thinner by the addition of 

 more naphtha, and is always readily dissolved by naphtha, 

 ether, or solution of potash, when it becomes hard or dry 

 in our stock-pots. 



Preparation and Preservation of Algce, (&c. — Mr. Ralfs 

 gives excellent directions for making preparations of algse 

 for microscopic investigations : — " The fluid found to 

 answer best is macij in the following way : to sixteen 

 parts of distilled water add one part of rectified spirits 

 of wine, and a few drops of creosote, sufficient to saturate 

 it ; stir in a small quantity of prepared chalk, and then 

 filter; with this fluid mix an equal measure of camphor- 

 water (water saturated with camphor); and before using, 

 strain off through a piece of fine linen. 



" This fluid I do not find to alter the appearance of 

 the endochrome of alo;8e more than distilled water alone 

 does after some time; there is certainly less probability of 

 confervoid filaments making their appearance in the pre« 

 parations ; and there would seem to be nothing to prevent 



