I N D U S T R I A L A N D ENGINEERING CHEMISTRY
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I I I I lb 20 /2 in Hours Figure &Effect of Type of Starter upon t h e pH. Cooking Temperature, 5 3 O C. A-Cheese made with 0.25 per cent go starter %Cheese made with 0.25 per cent 390 starter I
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Vol. 19, No. 11
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8 Age
Each pair of cheeses shown in Figures 3, 4, and 5 was made from the same lot of milk and as nearly alike as possible except for the differences noted. The ga starter, which was used in all the cheese, except the one represented by curve B in Figure 4, is a mixed type of bulgaricus organism and a mycoderm. The 99a starter is an old laboratory strain of Lactobacillus bulgaricus. The curves show the divergence in hydrogen-ion concentration which variations in the making of Swiss cheese produce, and indicate the
Age in Howrs Figure %-Effect of t h e pH. A-Cheese B-Cheese
Varying t h e Percentage of Starter upon Cooking Temperature, 5 3 O C. made with 2.0 per cent ga starter made with 0.125 per cent gu starter
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possibilities of this method of control of the manufacturing processes. Acknowledgment
The author is indebted, for valuable suggestions, to K. J. Matheson, who had charge of the manufacture of the cheese upon which these measurements were made.
Large-Capacity Incubators' By F. A. McDermott EASTERNALCOHOLCORPORATION, PRNN'SGROVE, N. J.
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T IS sometimes necessary to have considerably more incubator space than can be secured in the usual types of bacteriologic incubators, especially in plant control work and fermentation experiments, and the construction of an incubator room is not always justified or possible. An incubator providing for such use was described by the writer several years ago.2 Recently two other similar incubators have been constructed for the same purposes. The first of these measures 30 by 30 by 66 inches outside, and is built of two thicknesses of inch lumbgr, separated by a 1-inch space filled with powdered cork; this gives a total of nearly 10 cubic feet of available space in the two compartments. The second incubator consists of a single-walled box of '/ginch lumber, insulated with two layers of llrinch Celotex, one outside and one inside the box. The outside measurements of the insulated box are 33 inches front to back, 36 inches high, and 72 inches long. Two fixed shelves are provided, the lower one just raised off the bottom to provide for air circulation. Each shelf has 14 inches clear space above it, making the available capacity about 32 cubic feet. I n spite of the lighter and simpler construction of this second incubator, it has proved very satisfactory. The first of these new incubators is heated in the manner previously described.* I n the second, however, a much simpler scheme was used. An ordinary hair-drier, consisting of a small blast fan with a heating element in the outlet tube, operating on 110-volt a. c., is mounted on a laboratory stand in one back corner of the upper shelf; the thermoregulator 1Received August 1, 1927. *Tms JOURNAL, 6, €339 (1914).
is placed in the diagonally opposite front corner. A central thermometer is provided, which has shown only very slight variation-amply close for fermentation experiments with yeast-and thermometers placed in different parts of the interior have failed to show any significant variations in the temperature. The thermoregulator (Figure 1) used in both boxes consists essentially of an air thermometer having a cylindrical bulb of about 75 cc. capacity, making and breaking the current in the control circuit through a mercury column in a 1-mm. capillary tube sealed to the air thermometer. The
Figure 1 - T h e r m o regula tor
Fiaure 2-Electrical Circuit
November, 1927
IlVDUSTRI..IL AND ENGINEERING CHEMISTRY
second contact wire enters the capillary through the cup. Some variation in the setting with changes in atmosphericpressure is necessary but this is overcome to some extent by placing about 1 cc. of ether in the bulb before putting themercury in the capillary. Thermoregulators made of Willco metal, as well as various commercial types, have been tried, but were more or less unsatisfactory owing to chattering from the vibration when the fan was in operation. The control circuit (Figure 2) is operated by means of an electrolytic rectifier (Balkite) giving a 6-volt pulsating unidirectional current. A small storage battery is used as a balance, being charged when the relay is not energized and furnishing the extra current required when the relay operates. The relay is a Signal, type DB-1, taking about 0.25 ampere.
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The difficulties previously encountered3with a. c. thermostat systems are apparently entirely overcome by this system as both of these incubators have been in use for several months without any difficulty being experienced. It is, of course, necessary t o see that the electrolytic rectifier and storage battery are kept in operating condition. Acknowledgment
The circuit was outlined for the writer by the Fansteel Products Company, Korth Chicago, Ill., and he is indebted to J. W. Lawrie, of E. I. du Pone de Nemours and Company, Inc., for permission t o include the construction of the second incubator, which was made up for his work. 8
McDermott, J . A m . Chem. Soc., 37, 2381 (1915).
Deflocculation of Carbon Black by Saponin, Acacia, Gelatin, and Casein' By Robert M. Chapin BIOCHEMIC DIVISIOX,BIJRE.AKOF ANIMAL INDUSTRY, WASHINGTON, D . C.
The carbon black test for dejlocculating power, using both naked black and black artificially oiled, has been employed f o r the study of the dejlocculating powers, as compared with that of potassium palmitate, of commercial grades of saponin, acacia, gelath, and casein. Some ej'ects of variations in concentration, temperature, and reaction, and of the presence of octyl alcohol, are noted.
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HE carbon black method for the study of deflocculating power of soaps has been discussed by the writer,2 In spite of imperfections it appears to afford information which cannot yet be obtained in any better way.3 Consequently, its application has been extended to saponin, acacia, gelatin, and casein. It seemed best first to make a general survey of the comparative behaviors of these four substances with one another and with soap, then later to undertake such more intensive work as the preliminary data might warrant. For this reason, and because it was expected that the data might possess some practical applications, commercial grades of the substances, except soap, were employed.
100 grams of the original black were added, and the solvent was slowly expelled below boiling temperature, the last traces being removed in an oven a t 105" C. Throughout the process the mixture was frequently and thoroughly stirred with a spatula; finally it was brushed through a 100-mesh sieve and well mixed. In distinction from the original black it remained unwetted in contact with pure water. The quantity used in each test was 0.6 gram, corresponding to 0.5 gram of the original black. OCTYLALCOHOL-In some experiments secondary octyl alcohol was added to the solutions t o be tested in order to note the effect of the presence of a second surface-active
Technic of Experiments
The technic was essentially the same as that previously describeda2 Dilutions of the various stock solutions were prepared in test tubes and were heated for 30 minutes a t a temperature a t least 10" C. higher than the projected temperature of the test before being transferred to the constanttemperature bath. The filter papers were selecied to pass 10 cc. of water within 18 to 24 seconds after 20 CI:. had been poured on. I n case of deflocculants other than soaps the filtrates were diluted for measurement simply with water. The results of the measurements are expressed as the "color ratio" of each filtrate, meaning the ratio of the depth of color of a solution of that filtrate (originally 7 cc.) after dilution to 100 cc. to the depth of color of the Co-Ni-Cu standard, although in making the actual comparisons each filtrate was diluted to the most convenient volume. PREPARATIOK OF OILED CARBONBLACK-TO prepare oiled carbon black 20 grams of laxative mineral oil were dissolved in about 250 cc. of petroleum ether in a large beaker,
* Received April 16, 1927. * THISJOURNAL, 18, 1313 (1926);J. Oil Fat I n d . , 4, 15, 210 (1927). 8 Since this paper was submitted a new method for the estimation of deflocculating power has been described by Fall, J. Phys. Chem., 31, 801
(1927).
Figure I-Deflocculation-Concentration Curves of Pure Potassium Palmitate and of Gelatin a t 40° C. Curve I-Soap and naked carbon black; 11-Soap and oiled carbon black. 111-Soap and oiled carbon black plus octyl alcohol; IV-Gelatin '8nd oiled carbon black
substance, not itself a deflocculant. It was introduced by adding two drops (about 0.03 cc.) to each tube of solution (20 cc.) a t the time of its preparation from the stock solution. PoTAssIUhl PALMITATE-This substance was designed to serve as an ultimate standard against which all data might later be checked. It was prepared from palmitic acid of claimed melting point 81-62' C. and aqueous potassium hydroxide, and was proved to be practically neutral. The deflocculation-concentration curves are given in Figure 1. SAPoNm-The substance, of "purified" grade, was dis-
