140 ESSAY VII. 



benzoin dissolved, it ought to be evaporated, and afterwards 

 set by to crystallise. If you wish to give this salt a shining 

 appearance, dissolve it in a sufficient quantity in 6 oz., for 

 instance of water by gentle boiling, then strain it immediately, 

 while it is yet warm, through a cloth, into a glass vessel 

 which has been heated before ; you will thus have the 

 satisfaction to see a number of fine crystals shoot as soon as 

 the solution is grown cold. The water is then to be strained 

 from the crystals, and the rest of the salt, still suspended in 

 this water, is obtained by repeated evaporation and crystallisa- 

 tion. But as the flowers of benzoin are, on account of their 

 lightness, not easily pulverised, it may be best to keep the 

 salt in the form of a precipitate, which is always the finest 

 powder. To this consideration it may be added, that during 

 the crystallisation a great deal of salt is lost. 



I have recommended cloth for filtering the warm solution, 

 because I found it answer best. If blotting paper be used, 

 the salt sometimes crystallises in the filter itself, and 

 obstructs it. The filtration itself might be omitted, if it 

 were not unavoidable in order to purify the salt from about 

 2 grs. of resinous substance, which, having been mixed with 

 it during the preceding boilings, remain united with it during 

 the rest of the process. 



