I N D U S T R I A L d S D ESGISEERI-VG CHEMISTRY
86
analogous to stating that the shape of the viscobity-' F. curve should be similar to that of the viscosity-" C. curve. Relation of Viscosity
Vol. 19, No. 1
paper machines on Monday if the stock has stood since Saturday night. In the preceding paper data were presented dealing with the decrease in freeness of sulfite upon standing 3 and 4 weeks. Table I1 contains similar data for groun&ood. The decrease is probably due to slight fiber decomposition.
I n working with sulfite the question arose a3 to xhether temperature influenced freeness solely by virtue of its effect upon viscosity. That this was alm o s t exactly the case w a s e s t a b lished by determining the freeness of a stock suspended By A. M. McCollister and C. R. Wagner in a sugar solution, the temperature of THE PUREOIL Co., CHICAGO,ILL. which was high e n o u g h t o cause T7ERYuseful piece of apparatus for use on gas-analyzing the viscosity to be outfit's is shown in the accompanying sketch. It can the same as that of be easily made by any machinist from parts found in the shop. water at a much It was designed and is being used by the authors on a Fisher lower temperature. Universal gas analyzer, which is the Bureau of Standards This freeness value Orsat apparatus, but it can be applied on any gas-analyzing I was found to agree outfit or other appara'0 20 x, 40 so closelywiththatof tus where the accurate t DEGR[S C the same stock de- adjustment of a leveling Figure 3 termined in aque- bulb is desirable. ous suspension a t the lower temperature bqt a t the same The device consists viscosity. It was therefore concluded that for the same briefly of the following: stock suspending mediums of equal viscosities gave rise to A sliding block carrynearly equal freeness values, regardless of the temperatures ing the ring for the bulb, involved. which is actuated by a
Device for Adjusting the Leveling Bulb on a Gas-Analyzing Apparatus'
A
ol
b
Table I1
Run
Days
F, 20" C.
16 17 19
0 9 36
48 45 41
This conclusion is not valid for groundwood stocks. Freeness determinations were made in aqueous suspensions and the contents of the cup were combined with the effluents from the two orifices and filtered through a weighed cloth. The excess water was removed by suction and the damp fibers were suspended in a 20 per cent sugar solution, made up to 1 liter and again tested for freeness. As the average of two determinations, it was found that at a concentration of 19.70 per cent sugar, a temperature of 40.0' C., and a viscosity of 1.185 centipoises the freeness mas 46.0. With a water suspension, the freeness was 35.5 at 13.6' C., at which temperature the viscosity was the same as before. When the t e m p e r a t u r e Fvas 40.0' C., which corresponded to a tiscosity (for water) of 0.656 centipoise, the freeness was 59.5. At constant viscosity, then, freeness decreases with decreasing temperature, and a t constant temperature, freeness increases with decreasing viscosity.
I
"Slowing" of Stock
It is the experience of paperm a k e r s t h a t stock becomes somewhat slower upon standFigure 4 kgin the beaters and in the beater and machine chests even over a week-end. The effect is great enough to make itself evident in the operation of the
screw f i t t e d w i t h a k n u r l e d w h e e l . The main body of the device is carried on an ordinary r i n g - s t a n d c l a m p for coarse adjustments. An ordinary split ring was sawed in two about the middle of the shank and both of these ends were threaded. The sliding block was drilled and tapped to receive the ring and the m a i n b o d y was fitted with the clamp portion of the original ring. Rough adjustment is obtained by moving the whole device-and clamping t o the ring stand and very accurate adjustment is obtained by means of the screw and sliding block.
The accompanying cut shows ring actuated by rack and pinion which is an alternative method of construction. Either method should be satisfactory and need only to depend upon material available. 1
Received October 1, 1926.
Definition for Cultured Skimmed Milk Proposed by Standards Committee The Food Standards Committee has proposed the following definition and standard for cultured skimmed milk, "cultured buttermilk :" CULTURED SKIYMED MILE, "CULTURED BUTTERMILK." is the product obtained by souring skimmed milk, or partially skimmed milk, by means of special cultures of the streptococcus laclicus type. It contains not less than eight and five-tenths per cent (8.5%) of milk solids not fat.
Criticisms and suepestions regarding the DroDosed definition and- standard are i&ited from- food -officiais, consumers, the trade, and all interested parties. Communications should be addressed to the Secretary of the Food Standards Committee, B~~~~~ ,,f Chemistry, Washington, D. c., and reach him not later than February 15, 1927.
