LECTURE AND LABORATORY PRACTICE. 



169 



this bottle thi'ough the tube D connected to the bottle E above. 

 The saturated ammonia solution is drawn off for use through the 

 siphon F. If the column in this siphon breaks it can be started by 

 blowing through D with a pair of bellows. From C, after the solution 

 is saturated, the gas passes into the second wash-bottle G, fitted with 

 a valve opening downwards; this is to prevent non-saturated solution 

 being drawn back into C and so weakening this solution. This 

 happens if C is connected direct to H, C being completely filled with 

 water from H as soon as the ammonia is shut off. From G the gas 

 passes into H of about 10 litres capacity. In this, NH4OH of any 

 required strength can be made. In this laboratory 5E (approxi- 

 mately five times normal) NH4OH is the strength made in this 

 vessel. The strength is indicated by a rough specific gravity bulb J, 

 made from a piece of glass tubing and loaded with coloured water. 





The ammonia is passed in until this bulb sinks, the strength then 

 being 5E. As the solution cools the specific gravity will rise, and 

 more ammonia must be run in. When starting, the vessel H should 

 be not more than three-quarters full to allow for expansion. The 

 solution is drawn off, and fresh water added in the same way as 

 in C. Ammonia escaping from H can be absorbed in another vessel 

 of water, and this weak solution can be used for filling H. 



At the time the apparatus was fitted up liquid NH3 could be 

 purchased for Is. 6d. per lb., making the price of "880 NH4OH about 

 6d. per lb. ; so-called "880 NH4OH could be purchased for i^d. per 

 lb., therefore the NH4OH made in the above apparatus was appar- 

 ently dearer; but this, it is believed, is more than counterbalanced 

 by the loss in transferring and diluting the purchased "880 NH4OH. 

 On more than one occasion, in hot weather, the whole of a Winchester 

 quart has been lost through the rapid escape of the NH3 ; the trans- 

 ferring of the "880 NH4OH from a Winchester quart is also an objec- 

 tionable operation. : , 



The apparatus has been in use for several years without any 

 trouble being experienced. All the joints are made by means of I.R. 



