90 PBEPABATION AND MOUNTING 



CHAPTER IV. 



MOUNTING IN CANADA BALSAM. 



THE nature and use of this substance has been before spoken 

 of, so that the method of working with, it may be at once 

 described. 



Perfect dryness of the objects is, if possible, more neces- 

 sary in this mode of mounting than any other, as dampness 

 remaining in the object will assuredly cause a cloudiness to 

 make its appearance in a short time after it is fixed. Where 

 pressure does not injure the specimens, they are most suc- 

 cessfully treated when first dried betwixt the leaves of a 

 book, or in any other way which may prove -most convenient, 

 as noticed in Chapter III. 



Before describing the methods of proceeding with par- 

 ticular objects, general rules may be given which should be 

 observed in order to succeed in this branch of mounting. 



As the object is to be thoroughly immersed in the balsam, 

 it is evident that when it has once been covered, so it must 

 remain, unless we again free it by a process hereafter men- 

 tioned, which is very troublesome ; and on this account there 

 must be nothing whatever in the balsam except the object. 

 The inexperienced may think this an unnecessary caution ; 

 but the greatest difficulty he will meet with is to get rid of 

 minute bubbles of air, perhaps invisible to the naked eye, 

 which appear like small globules when under the microscope, 

 and render the slide unsightly, or even woithless. Balsam 

 dissolved in benzole will be found invaluable in mounting 

 without air-bubbles ; if a few are left in the specimen, by 

 the next morning they will have entirely disappeared. In 

 making this solution the balsam should be first boiled 

 gently till on dropping a small quantity into water it i* 



