172 



the material and the under layer does not dry. When a small area of liquid is exposed 

 for drying, the amount of moisture going off will be smaller than when a larger surface 

 is exposed. Many chemists prefer and recommend the use of powdered pumice instead 

 of sand. This allows the material to be absorbed. In the referee's opinion, the 

 results so obtained are of no more value than those with the use of sand. Where 

 numerous determinations are to be made, it is an easy matter to wash and clean the 

 sand, while to clean the pumice stone and remove all traces of the sirup is not so easy. 

 Lately the use of a roll of filter paper has been recommended as the absorbent. Wiley 

 (Bureau of Chemistry, Bui. 19, p. 49) recommended that in 1888, but it was thought 

 then to give low results. Mintz by this method reduced the time of drying from 

 seventeen hours to three. This method is practically the method of Adams for 

 milk, and should be given some consideration for next year. Finely flaked asbestos 

 as an absorbent material has been spoken of for drying milk. Browne & used it with 

 success in determinations of moisture in apple juices. It is further worthy of trial, 

 since the claim is made that it requires less time for drying than when sand or pumice 

 stone is used. The referee has made a few experiments with the Soxhlet oven, 

 where a current of dry air passes over the material, but the work has not progressed 

 far enough to make a report. A method that bids fair to supersede all others for 

 pure sugar solutions is the use of the refractometer. The comparison of this method 

 made by the collaborators shows its results to be nearer the vacuum results than those 

 of other methods. A second feature of the moisture work was a study of the effect of 

 increasing the time of heating or dryness on the determination. The following table 

 gives the average results obtained by the collaborators: 



Determinations of moisture increasing the time of drying. 



[Averages based on reports of five collaborators.] 



SUGAR. 



MOLASSES. 



From these figures the importance of not allowing the length of time to exceed ten 

 hours is noted, as active decomposition sets in. This decomposition was greater when 

 sand was used than when it was not, a result one would naturally expect. 



Centrbl. Zuckerind., 1908, 16 : 1102; Chemical Abstracts, 1908, 2 : 2632. 

 6 J. Amer. Chem. Soc., 1901, 23 : 873. 



