[miller] chemical LABORATORY RESEARCHES 59' 



cyanide solution (about 5 g. per litre.) The potassium cyanide 

 solution must be standardized by means of a babbit whose content 

 of copper has been determined gravimetrically. With low grade bab- 

 bits use a larger sample and filter off the lead chloride before add- 

 ing the ammonia. 



(Under direction of Professor L. J. Rogers) 



(18) A Rapid Method for Determining Nitrate in Chili Nitre 

 By Miss J.I. Lane 



In the technical analysis of Chili nitre, insoluble matter, moisture, 

 and chlorides are determined directly, and the nitrates by difference. 

 Devarda's direct method for nitrates is based on reduction to ammonia 

 by a special alloy; though accurate, this method is slow, it involves 

 the use of special apparatus and a comparatively small sample. In 

 the new method 2.5 g. of the Chili nitre is heated to 110°C in an 

 electric oven with 50 c.c. of twice normal sulphuric acid ; the loss of 

 acidity gives nitrates and chlorides, the latter of which is determined 

 directly. 



(Under direction of Professor L. J. Rogers) 



(19) The Rapid Determination of Arsenic in Mispickel and 



Smaltites 



By Professor L. J. Rogers and J. E. Clarke, B.A.Sc. 



Dissolve a sample containing about 0.2 g. arsenic in a mixture 

 of 10 c.c. cone, nitric acid and 10 c.c. cone, hydrochloric acid; dilute 

 to 100 c.c, add 2 g. tartaric acid dissolved in water, and then 

 5 c.c. saturated solution of microcosmic salt. Then add magnesia 

 mixture and ammonia in excess, in the usual manner; this precipitates 

 both arsenic and phosphorus. Allow to stand two hours, filter, wash 

 with dilute ammonia and once with water. Add precipitate and 

 paper to 70 c.c. hydrochloric acid (1 :1), cool, add 3 g. potassium iodide 

 (dissolved in water to 6 c.c.) swirl one minute, add 70 c.c. distilled 

 water and titrate at once with thiosulphate. Standardize the thio 

 by pure arsenious acid, using the same method. 



