AGEICULTURAL CHEMISTRY — AGROTECHNT. 313 



by means of the Cleveland open-fire tester and compared with the neutral 

 glycerids and total fatty acids of the fats and oils. The methods used for pre- 

 paring the neutral glycerids and total fatty acids are described. 



A new apparatus for fat extraction, I. Selecter {Jour. Indus, and Engin. 

 Che in., 7 (1913), No. 10, pp. 871, 812, fig. i).— The apparatus, which consists in 

 the main of three parts, (1) a condensing section, (2) a flooding section, and 

 (3) a reservoir, is described in detail and illustrated by a figure. Instead of 

 soaking the sample in the liquid ether, or other solvent, as is done in most of 

 the apparatus now in use, it is saturated with the vapor and periodically flooded 

 with redistilled liquid. In testing the apparatus with 10 samples of commercial 

 feeding stuffs it was found to give better extraction than either the straight 

 extraction or the Soxhlet methods. The apparatus is easy to manipulate, pre- 

 senting a smooth outer surface, which reduces the danger of breakage to a 

 minimum. The recovery of the solvent is also easy and rapid and entails no 

 loss of time. 



The estimation of raffinose by enzymotic hydrolysis, O. S. Hudson and 

 T. S. IlAUDiNG {Jour. Atncr. Chem. Soc, 37 {1915), No. 9, pp. 2193-2198).— A 

 method which depends on the polariscopic measurements of the solation before 

 and after treatment with melibiase has been devised, as follows : 



"The solution in which raflinose is to be estimated is first clarified with neutral 

 lead acetate and the excess of the lead removed as oxalate or sulphate. The 

 solution should not contain more than 13 per cent sugars, as a higher concen- 

 tration tends to retard the enzymotic hydrolysis. It must be also slightly acid, 

 but any free acid is to be avoided, so it is recommended that the solution be 

 accurately neutralized and then made slightly acid with from- 1 to 2 drops of 

 acetic acid per 100 cc. of solution. To 95 cc. of the sugar solution 5 cc. of top 

 yeast invertase solution is added, a few cubic centimeters of toluene shaken 

 with the mixture to prevent growth of micro-organisms, and allowed to stand 

 at room temperature until the rotation becomes constant. Fi-om 12 to 24 hours 

 are usually necessary, depending on the activity of the enzym solution. In the 

 solution at this stage all sucrose has been inverted and all rafiinose has been 

 hydrolyzed to melibiose and fructose by the invertase. 



" The next step consists in hydrolyzing the melibiose with melibiase and meas- 

 uring accurately the accompanying change in rotation. The rotation of the 

 solution should be accurately determined, and since it may now contain consid- 

 erable fructose its temperature must be carefully controlled for the polariscopic 

 observation. It is recommended that all readings be made at 20° C. . . . There 

 is now added to 95 cc. of the solution which has been hydrolyzed by invertase, 

 5 cc. of bottom yeast extract . . . and the rotation is read immediately after 

 mixing. It should correspond to the rotation that may be calculated from those 

 of the bottom yeast extract and the solution to which it was added, since the 

 reading is made before there has been sufficient time for the hydrolysis of 

 melibiose to proceed to a measurable extent. The solution should be preserved 

 with toluene, kept at room temperature, and its reading measured from day 

 to day. 



"A change of rotation in the levo direction indicates the hydrolysis of melibiose. 

 The specific rotation of this sugar is -{-143° and . . . changes to +70.4° on 

 hydrolysis. If the solutions are read in a 200-mm. tube in a saccharimeter, a 

 solution containing 1 gm. of melibiose per 100 cc. will change in rotation during 

 hydrolysis 4.18° Ventzke . . . Each degi-ee Ventzke change of rotation indi- 

 cates, therefore, 0.239 gm. melibiose per 100 cc. in the solution as finally consti- 

 tuted, a value which coi'responds to 0.352 gm. anhydrous raffinose." 



