Carborundum Disk Research Articles

Preparation of bulk oriented samples of AgBr and AgCl single crystals

AbstractThe paper describes in details a technology of bulk oriented samples of AgBr and AgCl single crystals. Some new methods have been used, i.e. cutting of boules with bakelitebonded carborundum disc saw and a preorientation of samples, made on cut‐off ends of boules cleft at liquid nitrogen temperature. Pre‐orientation has been realized with the aid of natural crystallographic edges occurring on cleft faces. Results are illustrated by photographs of some prepared samples with different shape.

Toxicity of Antiseptics for the Chick Embryo.

The resistance of the chick embryo to toxic substances is a subject which has been little explored in spite of the fact that the embryo is well adapted to a variety of bacteriological and physiological experiments. The developing egg consists of rapidly growing embryonic tissue in a perfect nutritional environment. It comes sealed in an ampule, the shell, which is readily opened for inoculation or other manipulation and easily sealed again for the period of rein-cubation. The original purpose of the present study was to determine whether the fertile egg could be used as a medium for testing the inactivating effect of antiseptics on viruses. Such studies could be made only if the normal physiology of the embryo is not greatly disturbed by the injection of such agents. Three tests were performed on different days with each substance. Embryonated eggs which had been incubated for 6 or 7 days were candled and the location of the embryo marked on the shell. This mark was kept uppermost until the inoculation was completed. A hole was drilled through the shell over the air sac by means of a 2 mm dental bur or a carborundum disc. The injection was made by means of a 2-inch, 20 gauge needle fitted to a tuberculin syringe. The needle was directed slightly upward and inserted 3 cm into the egg. The amount injected was 0.05 cc in each instance. This represents 1 part in 1000 of total egg weight, or the equivalent of 70 cc for a man weighing 70 kilos. The eggs were candled daily and the day of death noted. The results are shown in Table I.

Cultivation of Clostridium tetani in Unfertilized and Developing Fertilized Hens' Eggs

The employment of fertilized egg has proven of value for the cultivation of some bacteria and a number of filterable viruses. The chorio-allantoic membrane has been mostly used as the site of infection. Since the cultivation of anaerobic microorganisms in unfertilized and developing fertilized eggs has not been recorded, the preliminary results of such a study with an obligatory anaerobe, Cl. tetani, is herewith communicated.Technic. A pure toxigenic strain of Cl. tetani, recently isolated from a patient, was used. Cultures in cooked meat tube after 48 hours' growth were used as the inoculum. Unfertilized and developing fertilized hens' eggs of different age were employed. After the position of the embryo and the air sac was identified by transillumination and marked off and the shell opposite the air sac was sterilized with tincture of iodine, a small opening was made with a carborundum disc attached to a dental drill, leaving the inner shell membrane intact, which was later cut with a small knife after ...