DETERMINATION OF TOTAL SOLIDS. 11 



In the case of jellies, thoroughly mix to insure uniformity in sam- 

 pling. Place 00 grams in a 300 cc flask, dissolve in water by means 

 of frequent shaking, make up to the mark with water, and use aliquot 

 portions for the various determinations. With jellies that contain 

 starch or other insoluble material thoroughly mix before taking ali- 

 quot portions for the various determinations. 



JAMS, MARMALADES, PRESERVES, AND CANNED FRUITS. 



Thoroughly pulp the entire contents of the jar or can as directed 

 under fresh fruits. With this class of fruit products no effort need be 

 made to remove any of the nonedible portions except the pits. Pears 

 and similar fruits if put up as whole fruit are prepared for analysis 

 without the removal of the cores. 



In the examination of canned fruits it is often sufficient, when the 

 analysis is for the sole purpose of detecting adulterants, merely to 

 examine the sirups in which the fruits are preserved, as the sirup will 

 contain the added ingredients, such as glucose and preservatives, in 

 some products, however, such as Maraschino cherries, the fruit itself 

 is colored with a coal-tar dye which is insoluble in the sirup, and it is 

 necessary to pulp these in order to extract the color for identifica- 

 tion. In such a case the liquor may be separated and the relative 

 amounts of liquid and solid portions determined, as this ma} T be of 

 value in showing the presence of- an excessive amount of water. The 

 examination of the sirup need not be as complete as when the whole 

 fruit is taken. 



The price of the goods, as a rule, depends largely on the amount of 

 sugar in the sirup. 



DETERMINATION OF TOTAL SOLIDS. a 



The determination of total solids was the subject of considerable 

 work before the method of drying at 100 C. was finally adopted. The 

 drying of the samples in vacuo was not considered practicable, as few lab- 

 oratories are equipped to use this method, and the large bulk of work 

 also prohibited it. There can be no doubt, however, that this is the 

 most accurate method with samples containing large amounts of invert 



a McGiLL's WATER OVEN. A. McGill has devised a forced-draft water oven for 

 drying at temperatures between 60 and 90 C. The oven is heated by means of 

 ordinary gas burners, and the temperature is controlled by introducing at the bottom 

 of the oven a blast of air from a blower that is run by a small water motor. Before 

 discharging into the oven the air tube (which is about 1 inch in diameter) enters the 

 water chamber and is coiled a number of times in order to sufficiently warm the air 

 before it enters the oven. The exit end of the air tube is covered with a concavo- 

 convex disk in order to distribute the blast and to prevent harmful currents. By 

 regulating the burners and the flow of air a fairly constant temperature can be 

 obtained. The bottom of the oven is curved instead of flat, to prevent bumping 

 when the water is boiling, and a perforated plate serves as a false bottom. 



