13 



Tliis point is carrivecT at wlion the molasses is very tliick. It should then be 

 put in shallow vessels, and kept in a moderately warm room. It will soou 

 granulate, and should there remain sufficient gum to prevent rapid draining, 

 the sugar may be placed in a coarse bag, and pressed. 



Tlie boiling doAvn should be rapid, for a low heat, long continued, converts 

 the crystallizable sugar into uncrystallizable. One of the specimens forwarded 

 to this Department, made from excellent juice, but boiled slowly, upon analysis, 

 showed 64.11 per cent, of uncrystallizable sugar, and but 11.07 of cryr*talliza- 

 ble. 



The recommendation of the chemist to use lime may be objected to by many 

 farmers, v.hose past experience is not in its favor. But the chemist points to 

 the cause of former failures. Slow boiling and immature cane resulted in the 

 production of a large quantity of sugar that M^ould not crystallize, and this is 

 decomposed by the lime, producing brown compounds of lime. But crystalli- 

 zable sugar is not decomposed by it. Here, also, is seen the absolute necessity 

 of having a perfectly matured cane ; and, again, we would impress on the 

 minds of all that the only true standard of such ma^turity is the turning red of 

 the blades and stalk. In Louisiana the blades of the cane die as do the blades 

 of Indian corn, commencing with the lowest and ascending to the top. There 

 no part of the stalk is used for sugar purposes whei'c the blades ax-e still green, 

 but it is cut off at the top dead blade. The blades of sorghum die like the 

 gum-tree leaf, by turning red, and then gradually changing to brown in drying. 

 The first change shows that the vital action of the leaf has ceased, and that 

 the elaboration of the sap is completed. 



MILDEW. 



From recent correspondence, it is evident that the remarks on grape mildew, 

 in the last monthly report, were timely, and touched a subject of great import- 

 ance that is at present attracting much attention. In some sections of country 

 the rot in the grape has been making great havoc during the past and preced- 

 ing month ; and although (as may always be expected) there are many favored 

 situations where the crop is healthy, yet the liability to this disease is acknowl- 

 edged, and information is sought both with regard to this and other fungoid dis- 

 eases of the grape vine. 



For the benefit of those commencing observations on this subject it may be 

 useful to describe the general appearance and effects of grape mildew. 



It is believed by some that fungi will only attack disorganized tissue ; iu 

 other words, that it is rather a consequence than a cause of disease. While this 

 may in general be tnie, yet it is well known that some kinds of fungi will 

 at least spread on healthy vegetation. It has also been recorded that tlic fun- 

 gus development depends more upon the material body by which it is nouvisliei 

 than upon the seeds or sporules from which it springs; that cei-taiu acid Huids 

 continually produce certain species, and certain alkaline mixtures as constantly 

 yield other distinct kinds. Diversity of opinion on this subject is of all things 

 the most likely, since the diseases of plants are comparatively but little under- 

 stood, and first symptoms so difficult of detection, that the consequence may 

 readily be mistaken for the cause. 



There are two apparently distinct forms of mildew that attack the grape in 

 this climate. First, there is the form that seems to attach itself more particu- 

 larly to the foreign vine, or the varieties of vitis vinifcra. This may be de- 

 scribed as a white powdery-looking substance enveloping the upper surface of 

 the leaves, and occasionally spreading on the young wood, fruit stalks, and 

 berries. A similar fungus may frequently be observed on foreign gooseberries ; 

 also on the lilac, hawthorn, and on various other trees and weeds at certain 

 seasons. This has been termed au erysiphe, (spec.) Its effects on plants are 



