The mass after having been molded in the shape desired may be further hardened and set by the application of ice cloths or spraying with ether before the needle is withdrawn from the skin, yet this is hardly necessary, and the author advises against the practice for the reason that pressure of the needle prevents proper and free molding of the mass and renders the tissue liable to further injury by scraping its point to and fro subcutaneously, adding to the extent of the wound and the dangers of infection and repair. The skin immediately around the needle hole, after withdrawal of the needle, may be gently smoothed out with the dull rounded metal handle end of the bistoury to free the interdermal canal of any foreign matter. The skin about the needle hole is then gently washed with a fifty-per-cent solution of hydrogen peroxid, dried with a sterile cotton sponge and the opening sealed with a drop of collodion. Subsequent treatment of the parts will be considered later. =14. Solidification of Paraffin in Needle.=—This occurs only when paraffins of high melting points are employed in liquid form in the syringe, and is due to the rapid cooling of the paraffin in the small metallic cannulæ, or needle, wherein it sets more readily, since the volume contained therein is very small, often not more than two or three drops. This cooling establishes a pluglike formation in the distal end of the needle, which prevents a proper use of the syringe, often breakage, and when suddenly liberated by an extra pressure on the piston rod causes a rapid discharge of the contents of the syringe to an extent not desired with the result of hyperinjection. This fault was one of the most annoying in the early days of such injections when syringes of ordinary pattern, such as the Pravaz, or those built like the ordinary hypodermic, were used. It was not unusual to have the paraffin cool in the needle so quickly between the latter in the flame of an alcohol lamp that the syringe became unmanageable and broke in the hands of the operator. Since that time new and more useful syringes have been introduced by various operators which overcome this difficulty, yet with them, too, come the employment of semisolid paraffins or mixtures thereof. Yet, as some authors insist upon using paraffins of high melting points, it may be well to rehearse their methods of overcoming this annoying intraneedle solidification. Eckstein surrounds the syringe and needle shaft, except the tip of the needle, with a rubber tubing, as shown in Fig. 284, to act as an insulator, and thus, for a time at least, keep the preparation liquid. Before filling the syringe he heats it by several immersions in and internal washings of hot sterile water. To prevent the paraffin from setting in the exposed tip of the needle he draws into the filled syringe a few drops of hot water, which are injected into the tissues, causing no objection to the method.