60 



CHAP'J'EE V, 



ranks as a fixing agent because it kills and hardens with 

 such rapidity that structures have hardly time to get 

 deformed in the process ; very weak, because it possesses a 

 sufficiently energetic coagulating action and yet contains 

 enough water to have but a feeble dehydrating action. 

 The intermediate grades do not realise these conditionSj and 

 therefore should not be employed alone for fixing. But 

 they may be very useful in combination with other fixing 

 agents by enhancing their penetrating power ; 70 per cent, 

 is a good grade for this purpose. 



TcMe for diluting alcuhol (after GAY-LrssAc).— To use this table, find 

 in the upper horizontal row of figures the percentage of the alcohol that 

 it is desired to dilute, and in the vei-tical row to the left the percentage 

 of the alcohol it is desired to an-ive at. Then follow out the vertical 

 and horizontal rows headed respectively by these figures, and the figure 

 printed at the point of intersection of the two rows will show how many 

 volumes of water must te taken to reduce one hundred volumes of the 

 original alcohol to the required grade. 



Alcohol is an easily oxidisahle substance. Chromic acid, 



