REPORT OF THE CHEMIST. - 28} 
major portion of non-sugar has already been removed, upen the plan- 
tation, in scums, sediments, and molasses—substances which are yet 
left remaining with us in our treatment of juices. It is imperative 
with this article, in our work at least, that it be used in quantities 
quite beyond the utmost ability of filter presses to accommodate. 
Notwithstanding the meager results as yet secured, eventual suc- 
cess in the economic mechanical filtration of the entire body of defe- 
cated juice is not altogether despaired of. Its difficulties have been 
greatly underrated. All the juices thus far dealt with have been the 
product of milling under pressures attaining from 65 to 78 per cent. 
of these upon the weight of canes crushed. So successful through- 
out has been the routine work in this establishment with skimmings 
and settlings from all manner of canes and with many modes of defe- 
cation, and so small has been at any time the immediate improve- 
ment in the purity co-efficient attributable to it, and yet, by com- 
parison, so easy and rapid a second filtration, as to have forced a 
conviction that in but an exceedingly small part of the total non- 
sugar resides well nigh the whole difficulty. This probably minute 
portion of especially refractory material has been traced as an in- 
soluble, suspended impurity to raw juice direct from the rolls, which 
presents in the filter practically all the perplexities encountered after 
defecation and may be followed thence quite to the molasses. The 
microscope has not identified it at 100 diameters. Fermentation fails 
toremoveit. Although itself probably inert and harmless, it suffices 
to render most difficult or altogether impossible a process which, in 
effecting an immediate improvement, if only of several points in the 
exponent, would yet suffice before the by-product was reached to add 
directly or indirectly a decided increment to the otherwise possible 
rendement. Your success in filter-pressing carbonated diffusion 
juices this season of 1887-88 at the Magnolia Sration leads to the hope 
that this small part, whatever it may be, is either in great measure 
eliminated from the artificial juice by diffusion, or else is amenable 
to chemical treatment (other than carbonation), such as it is reason- 
able to suppose will not escape adequate research. In either case the 
benefit to accrue would become important to the local industry, the 
substitution of osmosis for pressure in juice extraction by large cen- 
tral factories now seeming as if eventually inevitable. 
It is proposed by the proprietor that the investigation of this sub- 
ject shall continue at this place uninterruptedly throughout another 
season. At his desire I express the hope that it may not be impossible 
with you to detail a chemist from your department to aid in this 
search for an improved defecation. It is not to be overlooked how, 
to the present, your Department, in pursuing its inquiries with re- 
spect of sugar manufacture, has neglected altogether the sulphur 
regimen universally found in Louisiana’s practice, excepting only at 
its previously chosen station. 
With much respect, sir, Iam yours, very truly, 
W. J. THOMPSON. 
Dr. H. W. WILEy, 
Chemist, U. S. Department of Agriculture, 
Washington. D. C. 
