30 VOELCKER on the Chemistry of Food. 



a tendency to scour animals fed upon the fresh root. Although 

 it has not yet been shown whether or not this acrid principle 

 disappears on storing away mangolds for some time, it is a well 

 known fact that, after a few months' keeping, mangolds have not 

 this tendency to scour, and are much more nutritious than in a 

 fresh state. The superior fattening value of stored mangolds, 

 when compared with the fresh root, may be due to the absence 

 of this acrid principle in old roots, but doubtless it must be attri- 

 buted also to the larger amount of sugar which stored mangolds 

 contain. An examination of fresh and old mangolds, namely, 

 has shown me that, on keeping, the pectin in the fresh roots is 

 gradually transformed into sugar, which appears to be more 

 conducive to the rapid fattening of beasts than pectin. For 

 these reasons mangold wurtzel ought not to be supplied to animals 

 before the latter end of December or the beginning of January. 



Before stating the composition of turnips and swedes I would 

 draw attention to the remarkable fact, which perhaps may be new 

 to some, that mangolds appear to be about the worst description 

 of roots that can be given to sheep. Two years ago I found this 

 to be the case, when feeding various lots of sheep, with a view 

 of ascertaining practically the relative value of different feeding 

 materials. For several days the sheep refused to eat the sliced 

 mangolds, and were content with the small quantity of hay which 

 was given to them at the same time, and only after 4 weeks they 

 became in some degree reconciled to the taste of mangolds, but 

 did not get on well upon this food. Although these sheep were 

 supplied with a fixed and limited quantity of hay, and as much 

 sliced mangolds as they would eat, I found at the end of four 

 months that they had not increased a single pound, whilst my 

 experimental sheep fed upon swedes and hay increased on an 

 average at the rate of 2i Ibs. per week. On further inquiry I have 

 learned that this observation is confirmed by many practical 

 feeders. Mangolds, therefore, ought not to be given to sheep. 

 This peculiarity of mangolds thus shows that a feeding substance 

 which, like this root, is justly esteemed on account of its fattening 

 properties when given to beasts, may not possess any great 

 nutritive value when given to sheep. Another direct proof is 

 here afforded of the fact, that the chemical composition of food 

 does not solely determine its adaptation to a particular purpose, 

 for, like mangolds, other feeding materials may be rich in nutri- 

 tive substances, and valuable when given to fattening beasts, 

 whilst it does not agree at all with the constitution of sheep. 



Turnips and Sivedes. The composition of different kinds of 

 turnips, and consequently their nutritive value, present us with 

 great variations. But inasmuch as one and the same variety, 

 when grown upon different soils, often presents us with quite as. 

 great variations in the amount of the various constituents which 

 are found in general in turnips or swedes, we cannot attach a 



