Chapter XIII

Compounds Containing Sulphur

157. Formation of Mercaptan (Section 317). - Hood. - Warm together about 1 gram of potassium ethyl sulphate, 1 gram of sodium sulphide, and 2 cc. of water. (Eq.) Note the odor.

158. Preparation of Potassium and Mercuric Thiocyanates (Section 324). - Caution. Potassium cyanide is poisonous and should not be handled with the fingers. Boil together 13 grams of potassium cyanide, 6 grams of flowers of sulphur and 50 cc. of water, until the sulphur has dissolved. (Eq.) Filter the solution and evaporate to crystallization (§9, page 6). Cool, filter off the crystals, dry them, and evaporate the mother-liquor again to crystallization. Collect the crystals as before. Weigh the product obtained.

Dissolve a few of the crystals in water, and add the solution to a solution of ferric chloride.

Add a saturated solution of potassium thiocyanate to a saturated solution of mercuric chloride; filter off the precipitate, and press it into cones about 0.5 inch high and set aside to dry.

Apply a lighted match to the top of a dried cone.

159. Formation of Potassium Xanthate (Section 325). - Make a saturated solution of potassium hydroxide in alcohol by warming an excess of the alkali with 15 cc. of alcohol. Cool the solution, decant off the clear liquid, and add 3 cc. of carbon disulphide. (Eq.) Allow the solution to cool. Filter off the crystals, wash them with a mixture of 5 cc. of alcohol and 5 cc. of ether and dry them. Dissolve a little of the compound in water, and add a few drops of a solution of copper sulphate. The brownish-black precipitate of cupric xanthate changes immediately to yellow cuprous xanthate.