August, 1928
INDUSTRIAL AND ENGINEERlNG CHEMISTRY
a negative catalyst alone. This set shows a slight bodying action. Sets 5 and 6 show the effect of sodium and calcium oleate on the rate of bodying. The time to acquire a given body is about one-half of that required in Set 1. The oleates of sodium and calcium lower the surface tension and thus permit the immediate formation of a thick, stable foam. The interface between the oil and the air is increased greatly, permitting more rapid absorption of oxygen. Set 7 shows the variation of the constants, when free fatty acids of linseed oil are bodied by blowing. The acid value is reduced, showing that the carboxyl group is affected in the course of the reaction. In Set 8 samples of linseed oil were heated in an inert atmosphere (COZ) for 8 hours a t various temperatures. The hexabromide number falls off steadily and reaches zero in less than 8 hours a t 280' C. These samples were then blown to a given body (refractive index 1.4880). On the premise that one ethylene linkage in each molecule of linolenic acid has been saturated by heating, the decrease in hexabromide number is quite comparable to the decrease in unsaturation as measured by the decrease in iodine number. The oil has also bodied somewhat. It would seem, therefore, that the shorter time required to oxidize the previously heated oils is due to previous coupling reactions. The coupling reactions have produced molecules which cause the oil to have different characteristics-e. g., surface tension-from that of the original oil. The results and the products obtained in this run are not without significance in indicating that purposed combinations of treatments, each of which accentuates a certain type of reaction, will enable us to get a greater variety of products desired for various industrial processes and will also enable us often to get a certain desired product more surely and more easily than when we use one treatment-. g., blowing, heating, or raying, alone. Meyers5 has prepared various metallic salts of thioglycolic acid and has indicated some of their properties. The present writers found that thioglycolic acid (0.5 per 6
J . Lob. Clin. Med., 6, 359 (1921).
811
cent) added to the oil retards the bodying as does a-naphthol. They also made the interesting discovery that the addition of this acid precipitates the metals of metallic driers present in the oil. The precipitation is practically quantitative, as shown by the results in Table 111. The precipitated lead, manganese, cobalt, and iron derivatives of thioglycolic acid are insoluble in petroleum ether or in naphtha. The precipitate can therefore be washed free from oil and weighed. Thick oils made by heat-bodying or blowing can be diluted with naphtha before adding the thioglycolic acid. The metals are then completely precipitated from the diluted heavy-bodied oils in which they had been previously incorporated by heating. A few preliminary tests were made with resin varnishes. The metals were precipitated by the thioglycolic acid as in the case of raw or bodied oils. For scientific purposes the use of thioglycolic acid enables an investigator to study whether the function of a given drier lies in starting a reaction and building up bodies that then react on each other in later stages of the process (blowing, cooking, etc.), or whether the metal drier is needed constantly during the entire process to stimulate a certain reaction or type of reaction. The drier can be removed a t any time during the process and comparison thus obtained of its effect (1) when present all through the process, and (2) when present for only part of the process. It now becomes possible to use certain driers to promote desired reactions during the heating or blowing process and then to remove part or all of these driers from the processed oil and introduce the type and quantity of driers desired for the subsequent use of the product. This avoids the compromise necessary when the drier is used to promote reactions in processing, and then remains in the product and influences the oxidation of the product in paints, varnishes, and other protective coatings. The act that free fatty acids can be oxidized at 30" C. to a heavy body is of interest as indicative of reactions in the early part of the drying process leading to the formation of molecules of sufficient complexity to be a factor in the adsorption process, which seems to play an important role in the latter part of the process of solidification of drying oils.
Dialysis of Putrescible Liquids' 0.M. Urbain URBAIN
& HUNT,209 SOUTH
HE dialyses of putrescible liquids, such as domestic sewage and the waste solutions from tanneries, creameries, canneries, etc., present some unique problems. If the results of the dialyses are to be reasonably accurate, the bacterial decomposition and the oxidation of the putrescible material in such solutions during dialysis must be eliminated. A dialyzer constructed as shown in the accompanying drawing has been used for a number of years with excellent results. The dialyzing water consisted of distilled water, the dissolved oxygen of which had been expelled by boiling. A 25-gallon, bottle-shaped, tinned-copper vessel was used for this purpose. After boiling, oxygen traps were attached to prevent the entry of oxygen during the cooling period. The metal cover was then sealed in place over the dialyzing compartment. The air was removed from the compartment by aspirating nitrogen through the area by means of the petcocks in the metal cover. Dialyzing trays made of S & 1
Received May 14, 1928.
HIGH ST.,
COLWMBUS, OHIO
S parchment paper were used and found to be very satisfactory. Several samples may be dialyzed at one time. The dialyzing area was maintained at a temperature near 0" C. by means of the ice jacket.
,
p~,Iss,v"
;
~ ~ ~ i O r r r~ r n ,~,~) ~ " ' ' " , ~ D ~ ' V Z J * = WIT=-
4 ICE J"CKE7 5 DIAL
