1920] AGRICULTURAL CHEMISTRY — AGROTECHNY. 715 



culty in intei'preting the scale readings in terms of color concentration. From 

 a series of readings on various strength solutions of the same raw sugar, it 

 was found that the readings in any series (considered as decimal fractions) 

 run in powers of the first reading of the series if multiples of a unit of material 

 be used. This is due to the mechani<'al make-up of the instrument and holds 

 whatever color screen or kind of material is used. 



This relationship between the scale readings smd tiie amount of material 

 taken can be expres.sed by the e(|uation y —K", where y = any scale reading, K— 

 the scale reading for one unit of the material, and x ='the number of units of 

 material which will give the scale reading y. By means of this equation the 

 color of two materials may be compared if the scale readings for eipial quantities 

 are known, or all scale readings may be compared to a standard. A table lias 

 also been calculated which gives the uiuts of color corresponding to each scale 

 reading from 100 to 1. This may be used for the rapid determination of the 

 color of raw sugars as follows : 



Twenty gm. of the sugar is dissolved in distilled venter, made iq* to lOU cc, 

 filtered through paper in wliicii is placed 2 or 3 teaspoonfuls of kieselguhr, 

 and refiltered until the .solution is clear. Twenty-five cc. of this solution is 

 transferred to the observation cell on the right of the instrument, and an equal 

 amount of distilled water is placed in the left hand cell. The solution is read 

 through each of the 3 screens, the readings are recorded, and the corresponding 

 color units read from the table. The color of the sugar is calculated by adding 

 the color units thus obtained and dividing by 3. Typical results of color deter- 

 minations on raw and i-efinery stigars ax"e reported. 



Fruit evaporation and by-products, O. I\I. Morris (Wdsliiiuiton .S7rt. Bui. 

 15.') (1920), pp. 33, 34)- — Preliminary work on fruit evaporation and by-products 

 has indicated that dipping the fruit in a solution before drying is of no particular 

 advantage. Added circulation with a fan was found to increase greatly the 

 rate of drying without Increasing the quantity of heat generated. Tests made 

 with apple siiiq) to determine whether the-boiling point can be used as a test 

 for the keeping qualities of the material indicated that at the elevation of 

 Pullman, 2,5,00 ft., sirup concentrated to a boiling point of 103° (L was not 

 uniformly satisfactory, but that when i-oneentrated to a boiling point of 105° 

 tile sirup kept perfectly. 



The evaporation of grapes, W. V. f'lu^Kss, A. W. Christie, and F. C. H. 

 Fi.ossFKDKR {California Sta. Bui. .322 {li>20}, pp. J,21-J,ll, figs. 12).— In this bul- 

 letin are presented the results of an investigation of different methods of con- 

 structing and operating evaporators for tlie drying of raisin grapes, wine grapes, 

 cull table grapes, and sec-ond-crop Muscats. 



Following a brief discussion of the principles of evaporation, a detailed de- 

 .scriptlon is given of an evaporator of the horizontal tunnel, air-blast type and 

 of 6 tons of fresh fruit capacity which was constructed on the university farm 

 in 1919 and used for the experimental work here reported. The discussion of 

 the evaporator includes a list of materials and cost of construction, a descrip- 

 tion with accompanying diagrams of the original evaporator, an explanation of 

 the course followed by the grajies at the evaporator, suggested revisions in the 

 plan of the evaporator resulting from the experience gained in its u.se, and 

 estimates of the cost of operation of such an evaporator. 



The exjierimental work reported upon includes studies of the effect of dipping 

 grapes in hot lye solution before drying; the relative merits of drying fruit in 

 the sun and in evaporators ; the effect of suliihuring and of temperature on the 

 quality and rate of drying; a comparison of the efficiency of trays, burners, 

 fans, and fuel of different types; a study of permissible ranges of moisture 



