[Illustration: FIG. 284.—ECKSTEIN METHOD OF INSULATING NEEDLE AND SYRINGE.] Paget and Harmon Smith warm the needle in hot sterilized or even boiling water. Previous to this Smith cools the contents of the syringe drawn into it at a temperature of 120° F. by immersing the latter in a bath of sterilized water at a temperature of 80° F. From the above it will be noted that Smith advocates using the injections in semisolid state being ejected in a thin, cylindrical thread. A syringe of special construction, as referred to later, is, of course, required for such work. Quinlan has invented a so-called paraffin heater, as shown in Fig. 285, in which the paraffin is kept in solution by the syringe being surrounded by a continuous flow of hot water. A plain and very objectionable syringe is shown in the illustration, and while the preparation in the syringe is thus kept in a liquid state the solidification in the needle is not overcome. [Illustration: FIG. 285.—QUINLAN PARAFFIN HEATER.] Downie winds fine platinum wire about the needle through which he passes the current from a storage battery to keep the needle hot, yet such an arrangement is obviously difficult of manipulation, and when paraffins of high melting points are employed it is quite likely that a plug is formed in the exposed point of the needle. Karewski has introduced a syringe having a jacket through which hot water is allowed to circulate, while similar instruments have been originated by Pflugh and De Cazeneuve. None of these overcome the difficulty in question. Viollet went even further by inventing a syringe surrounded with a coil of resistance wire, heated by an electrical current, and Delangre, Ewald, and Moszkowicz use special thermophorm sleeves over the syringe proper; all, however, offering the same objection in the exposure of a part of the needle in which temperature of the liquid must necessarily be lowered, or be low enough to cause plugging, the very fault for which all these modifications have incidentally been urged, as the greater amount of paraffin in the syringe itself is as a rule large enough to retain sufficient heat to permit of its ejection, if the injection is made as expeditiously as possible. The objection of the setting of the paraffin in the barrel of the syringe has never hampered any operator, the difficulty in these instances having been entirely due to the obstruction offered its ejection by the threadlike plug obstructing the metal cannula before it; the barrel, being glass, retains its temperature more readily than the thin metal needle, hence the difficulty.