OBJECTS AND THEIR MOUNTING, 45 



follows : Take a slip of glass and cover it on one side with a coat of 

 painter's white-lead, leaving a space in the middle large enough to 

 contain the object to be mounted ; when this coat is dry, add another, 

 and proceed thus until a sufficient thickness is obtained for the enclo- 

 sure of the object to be mounted. The next thing is to procure a 

 clear piece of mica, free from veins and flaws, and rather smaller than 

 the slip of glass. Fill the cavity with spirits of wine, place the 

 object therein, and cover it with the plate of mica, which must be 

 brought into close contact with the white lead, by gently pressing it 

 with a smooth piece of wood from one extremity to the other, so as 

 perfectly to expel the air bubbles. In a few days, the white lead will 

 have become hard ; and if the mica be sound, the enclosed specimen 

 may be preserved for years Instead of the mica, a piece of thin 

 glass of the same size as the former may be laid on the surface of the 

 white lead, and the edges kept together with marine glue. 



40. GOADB\'S METHOD. But the best and most valuable pre- 

 servative fluid with which we are acquainted, is that discovered by 

 Mr. Goadby, of which the following is the formula* : 



Bay Salt 4 ounces 



Alum 2 ounces 



Corrosive Sublimate . . 4 grains 



Boiling water 2 quarts. 



These ingredients are to be stirred well together, and when cold, 

 strained. 



Preparations immersed in this fluid keep their colour well, even 

 those possessing a delicate rose tint, such as the blood corpuscules. 

 In mounting objects for the microscope with this fluid, the following 

 method may be adopted. If the object be flat, it will be only neces- 

 sary to place it on a slip of glass, to drop on to it a little of the fluid, 

 and then press on to it another piece of glass of a similar size the 

 superfluous moisture is then to be wiped from the edges of the two 

 pieces of glass, and they are to be kept together by brushing the 

 edges over either with gold size or marine glue. If the object be not 



* This solution is equally valuable to the zoologist. No preservative fluid 

 hitherto discovered, is equal to that of Mr. Goadby. Specimens thus put up, pre- 

 serve all their beauty of form, flexibility, and natural colour. 



c 3 



