APPENDIX. 



862, The Usual Alcohols, 



Strength. 



Made approximately as under. 



Observations. 



Absolute 



95 

 per cent. 



90 

 per cent, 



See 63. The so-called " ah- 

 solute alcohol " of commerce 

 is generally of about 98 per 

 cent, strength. 



This is the average strength of 

 the common strong commer- 

 cial alcohol, which ranges in 

 general from 94 per cent, to 

 96 per cent, according to 

 temperature. The strength 

 of this, or of the following, 

 should be determined by 

 means of an areometer (Gay 

 Lussac's being very con- 

 venient), so as to form a start- 

 ing-point for the following 

 mixtures. 



May be made approxi- 

 mately by taking 100 

 vols. 95 per cent, alco- 

 hol, and 5'5 vols. water. 



This grade is not neces- 

 sary for ordinary work. 



This is the usual grade 

 for dehydrating before 

 clearing. It is the 

 highest grade that 

 should be used for de- 

 hydrating celloidin sec- 

 tions. 



This is the usual strength 

 of the strongest com- 

 mercial Methylated 

 Spirit, which (if free 

 from mineral naphtha) 

 maybe taken instead of 

 pure alcohol for com- 

 mon work. If naphtha 

 be present the alcohol 

 becomes turbid on the 

 addition of water. Oil 

 of bergamot will clear 

 from this grade. 



