JULY 15, 1936
ANALYTICAL EDITION
was reduced in each case. I n contrast with this, when the outer thin was mixed with the thick, the proteolytic activity of the mixture was greater than that of the thick alone in five cases, practically equal in one, and less in one of the seven determinations. These results indicate that most of the inhibitory substance responsible for the resistance of raw egg white of freshly laid eggs to proteolytic activity is located in the inner thin fraction.
311
Literature Cited Balls and Swenson, ENa. CHEM,, 26, 570-2 (1934). (2) Hughes, Scott, and Antelyes, unpublished data. (3) Needham, "Chemical Embryology," Vol. 111,p. 1307, New York, Macmillan Co., 1931. RECEIVEDApril 27, 1936. Presented before the Division of Biological Chemistry at the 9 l s t Meeting of the American Chemical Society, Kansas City, Mo., April 13 t o 17, 1936. Contribution No. 204, Department of Chemistry, Contribution No. 96, Department of Poultry Husbandry.
Preparation of Flattened Copper Tubing Coils EDW.IRD P. BARRETT AND WILLIAM L. BARRETT, Bureau of Mines, Pittsburgh, Pa.
numerous joints made by this method has failed; they are tight and strong, and do not decrease the cross-sectional area of the flattened tubing. The details of the joint arc shown in Figure 2. A is the jig for forming the sleeve, B the parts of the joint, and C the completed joint in a section of flattened copper tubing. A piece of copper
tubing about 1.25 inches long, having an inside diameter equivalent to the outside diameter of the tubing to be joined, was shaped on the jig, A , the cross section of which was the same as that of the flattened tubing to be joined. If a piece of the larger tubing is not available, the short piece may be easily made by turning and drilling a piece of copper rod.
FIGURE1. FLATTENED COPPERTUBING COILIN
THE
Two methods of completing the joint have been used: (1) The inside of the sleeve and about an inch of the end of each piece of tubing were coated with silver solder. Borax was used as a flux. The silver-solder-coated ends were inserted in the sleeve as shown in C and sweated together by heating with a smalltipped oxy-acetylene torch, after which the ends of b were silver-soldered t o a and c,
e+-
MAKING
F
LATTENED copper tubing may be used more advantageously than circular tubing in many types of laboratory and experimental apparatus. FORMING THE FLATTENED TUBING.Flattened copper tubing may be readily formed by drawing circular tubing through special dies. I n 1926 William L. Barrett made two dies for forming flattened copper tubing: one for forming tubing 0.5625 X 0.1875 inch with an opening 0.4375 X 0.0625 inch from 0.375-inch copper tubing having 0.0625-inch wall; the other for forming tubing 0.75 X 0.21875 inch with an opening 0.625 X 0.09375 inch from 0.5625-inch tubing having 0.0625-inch wall. MAKINGCOILS OF FLATTENED TUBING. Numerous spirally wound coils of flattened copper tubing have been made in the metallurgical laboratories of the Pittsburgh Station of the United States Bureau of Mines, a mandrel being made for each diameter of coil required. The photograph, Figure 1, shows a coil in the making. The mandrel, M , 7 inches in diameter, is mounted in a lathe. Flattened copper tubing N was formed as circular copper tubing C was drawn through the die, P,and simultaneously wound on the mandrel. The mandrel was hand-rotated by means of bars inserted into the holes, R. The curved tool, 8, held the turns together and prevented the flattened tubing from twisting as it was wound onto the mandrel.
JOINING FLATTENED COPPERTUBING.It was often necessary to join pieces of flattened copper tubing. None of the
' FIGURE
\LY 2.
METHOD OF
I
Y
JOININGFLATTENED COPPERTUBING
respectively. (2) The ends of the tubing were inserted in the sleeve as shown in C and the ends of b silver-soldered to a and c, respectively. RECEIVBD April 27, 1936.
