REPORT OF THE CHEMIST. 



117 



in the boiler may be. The top of the box is arranged like the roof of a 

 house and carries a ventilating flue with a damper. 



The box rests on leaden supports in a lead box, over the bottom of 

 which is placed a layer of pumice-stone saturated with sulphuric acid. 

 All the air which enters the box must pass over this desiccating iiiate- 

 lial. It therefore reaches the substances to be dried in the most favor- 

 tible conditions. Each layer of tubes is provided with a thermoiuetm-. 

 The trap is set so that no water will accumulate in the pipes and at the 

 same time as little steam escape as possible. 



Experience has shown that with 20 pounds pressure of steam the mid- 

 dle system of tubes will give a constant temperature of 100° 0. The 

 bottom and top floors are a little cooler. 



With 40 pounds pressure the central floor will show a temperature of 

 107° C. when the damper is closed. The dishes containing the sub- 

 stances to be dried are carried in trays made of wire gauze. A box of 

 the size described will hold more than a hundred 3-inch dishes. 



OUTLINE OF METHOD. 



About 2 grams of the substance are taken and dissolved in alcohol. 

 The alcohol should be of about 70 per cent, strength, so that about 5 

 cubic centimeters of it will dissolve the samples taken. If the sample 

 contains much dextrine a weaker alcohol may be used. The platinum 

 dish and short glass stirring-rod are weighed together. Fine sifted 

 sand previously gently ignited, washed with distilled water, and dried 

 at 100° 0., is now poured into the dish. About 15 grams are enough. 

 The alcoholic solution of the sample is at once taken up by capillary 

 attraction. The sample is then dried in the oven for half an hour to 

 one hour. It is then removed, and, when cooled to about 70° C, 5 cubic 

 centimeters absolute alcohol are added and thoroughly mixed with the 

 contents of the dish by the stirring-rod. 



The sample is allowed to stand for a few minutes until the absolute 

 alcohol has had opportunity to penetrate all parts of the saccharine 

 sand. The dish is then warmed at 70° C. to 75° 0. for a few moments 

 until nearly all the alcohol is driven off. It is then placed in the oven 

 and dried to constant weight. 



DATA OF WORK. 



The first attempts at drying were made in an ordinary air-bath, the 

 final temperature being carried up to 110° C. Owing to the great diffi- 

 culty in securing an even temperature in such a bath, the results obtained 

 were very unsatisfactory. 



The following per cents, were some of the best of those obtained with 

 !i sorghum sirup : 



Other duplicate trials differed so widely as to cause the abandonment 

 of the work at that temperature. 



