376 ELEMENTARY CHEMICAL MICROSCOPY 



CHLORIDES. 



a. With Silver Nitrate. See Silver, page 331. 



b. With Lead Nitrate. See Lead, 'page 325, 



CHLORATES. 



a. Test the material with Rubidium Chloride and a little Potas- 

 sium Permanganate to be sure perchlorates are absent (see Ex- 

 periment a, Method IX, page 262). Then Convert into Perchlo- 

 rates as follows: 



Dissolve a little of the material in a drop of water at the corner 

 of an object slide, evaporate to dryness. Add a drop of sul- 

 phuric acid, evaporate to dryness and heat until white fumes 

 escape. Add a second drop of acid and heat until the excess 

 of sulphuric acid has been driven off. Cool. Add a tiny drop 

 of potassium permanganate (just sufficient to color the drop) 

 and a crystal of rubidium chloride. Allow to stand for a short 

 time and examine. Characteristic crystals of rubidium per- 

 chlorate will separate, colored pink or violet through adsorption 

 of the permanganate. 



The chlorate is only partially converted into the perchlorate, 

 hence this test is not .always successful, and is of little value in 

 complex mixtures. 



CHROMATES; BICHROMATES. 



a. Test with Silver Nitrate in nitric acid solution. See Silver, 

 page 334; Chromium, page 357. 



b. Test with Strontium Acetate. See page 301. 



c. Bichromates give no separation of crystals with Manganous 

 Sulphate; Chromates do. See Manganese, page 360. 



CYANIDES. 



a. Place the material in the gla.ss crucible of apparatus, Fig. 

 130, page 245; moisten with dilute sulphuric acid, cover with a 

 slide bearing a drop of silver nitrate. If no tiny prismatic 

 crystals are obtained and no clouding of the silver nitrate, 

 cyanides are absent. If a clouding of the drop results, make a 

 Iresh test, this time substituting for the sulphuric acid, a saturated 



