Pond, — On the Sugar Values of Beet-roots. 369 



out, the root being richer in sugar in the lower than in the upper portion. 

 Having thus obtained a fair average of the root, I have accurately weighed 

 and then pulped the assay portion in a mortar with distilled water, and 

 inverted the sugar in the ordinary manner with dilute sulphuric acid, 

 making my quantity up to a known amount, from which I have charged 

 the burette in the ordinary way. 



Fearful of the conversion of the woody fibre into glucose, and a conse- 

 quent false increase of the results, I have frequently checked this process 

 by filtering off the diffused juice from the pulp, well washing the latter, and 

 then inverting the sugar contained, but in all these cases the pulp still 

 retains a small amount of saccharine matter, but the difference between 

 these two methods is so small as not to cause much disparity, and here I 

 will give one experiment to show the difference. A root of the Eed-top 

 Imperial, weighing 2f lbs., was taken, and two cores from the puncture tube 

 fairly chosen, to the weight of 2 grammes each, pulped, and the one 

 inverted with the pulp, the second filtered, the pulp washed and the filtrate 

 inverted ; the percentage of sugar being 9*82 in the first portion, and 9*50 

 in the second. The difference I attribute to the sugar still left in the pulp. 

 The methods by which I have determined the percentages of sugar, have 

 been with Fehling's copper solution, and Knapp's mercuric cyanide solution, 

 both volumetric analyses, the former being in my opinion the most accurate. 

 To ensure precision, I have frequently inverted pure anhydrous cane sugar, 

 and estimated my standard solutions with it, and therefore feel justified in 

 saying that the analyses given by me in this j)aper are reliable. 



In addition to the chemical analysis we have the specific gravity, this 

 being a very reliable guide to the value of sugar present, and this I have 

 obtained after expression of the juice on several occasions by means of the 

 balance. Before concluding this portion of my paper on the chemical 

 manipulations, it will be interesting in a few cases to note the relative pro- 

 portions between the chemical values and the specific gravities. 



The root already mentioned as having been received from Mr. "Walker, 

 Cambridge, and which I estimated to contain 15 per cent, of sugar, was- 

 grated until it had lost weight equal to 200 -grammes, the juice from which 

 being ex^Dressed equalled 128 c.c, added water to the pulp and macerated, 

 pressed to near dryness and made up the amount with water to 200 c.c. 

 Found the specific gi^avity of the pure juice before adding water to be 

 1*08087, and the percentage of cane sugar in the 200 c.c. to be 14-35, the 

 difference being the amount of sugar still retained by the pulp. Again a 

 root from Mr. O'Neill was grated, lib. of which yielded 14|-ozs., weight of 

 juice, and If oz. pulp. The specific gravity equalled 1-0628, and the per- 

 centage of sugar in the juice was 11 "4. 



39 



