132 THE ANALYST. APPARATUS. A Simple Apparatus for Drying Substances under reduced pressure' at any required Temperature. F. Pregl. (Zeit. and. Chem. 1901 XI. 781-785.)-The device shown in the figure is of use not only for drying hygroscopic eubstances but is also particularly suitable for determining the water of crystallization of crystals. As a rule substances are dried to constant weight within half a day. I t consists of a thick glase tube about 41 centi-metres in length and 20 millimetres in diameter which i6 paesed through side tubulures in a drying oven and kept in position by corks. The substance to be dried is placed in the boat S whilst the drying material (phosphorus pentoxide sulphuric acid on puniioe-stone etc.) is contained in the larger boat which is wrapped round with copper foil to guard against possible spirting.The open end of the tube is closed with arubber cork through which is passed a tube with a mercury manometer and stopcock. After exhausting the air in the tube by means of a pump the stopcock is closed and the tube heated to the required temperature any leakage of air through the cork being indicated by the manometer. C. A. M. Receiver for Fractional Distillation under Diminished Pressure. W. Burstyn. (Oesterr. Chem. Zeit. 1901 iv. 563.)-The three small tubes which serve as actual receivers are lightly held together by means of a rubber ring and they are dropped into the larger tube as shown. By having the end of the condenser tube slightly bent its orifice can be brought opposite the mouth of each of the small receivers in succession by simply rotating the outer vessel on its rubber cork.The tube at the lower end of the main vessel leads to the pump. The rubber cork should be lubricated with atrong pure glycerin which is better tha THE ANALYST 133 collodion as it does not attack the rubber has no can be quickly washed off with water. appreciable vapour tension and F. H. L. Laboratory Appliances. R. Gnehm. (Zeds. f. aqew. G'hRm. xiv. 1208.)-Fig. 1 shows a simple mill for pulverizing solid bodies treating cellulose with strong soda lye etc. The iron tube A about 100 millimetres in diameter is at either end screwed to the two brass plates C,C, which are pro-vided with extensions .DID, that act as an axle and rest in the supports E,E,.To introduce or remove the substance the plate C is unscrewed. At the same tinie a number of iron cylinders W or balls E are intro-duced. For operations which require continual stirring, together with heating under an inverted condenser and the introduction of liquid the appliance shown in Fig. 2 F3 The drum is turned by means of the pulley F. Ffg. 1 Ffg. 2. may be used The stirrer is driven from the pulley G and rotates in the tube P, which is made of glass or metal and is fixed by means of the cork E into the appliance. A. M. Apparatus for Sublimations. C. Nicolaysen. (Che?n. Zeit. 1901 xxv. 1031.)-This apparatus consists of a boiling-tube about 6 centimetres in diameter inside which a narrower tube is supported as shown by the sketch. Tubes E and F serve for the entry and exit of cooling water into the inner tube.C is open at both ends. Small quantities of materials can be safely deposited on the outside of D without danger of the sublimate dropping; if it be desired to collect larger amounts, a small basin might be slung under D so as to collect any falling matter. F. H. L 134 THE ANALYST. A Drying Oven for Temperatures exceeding 100" C. (Chem. Zeit. 1901, xxv. 1086.)-This is an apparatus which can be set to give any desired temperature up to 105" (or even 110" if necessary) working with pure water boiling under pressure. The thermostat shown on the right of the oven in the diagram contains about 140 grammes of mercury and is so constructed that when the tem-perature and therefore pressure rises to the pre-determined point the mercury cuts off the gas supply, leaving only a pilot flame alight.By introducing small extra quantities of mercuryinto the tube the maximum temperature can be lowered by a degree at a time. A brass-jacketed gauge-glass is also fitted at the side On the top is a valve which admits air to the steam space when the oven is cold. The front slopes as shown so that the door needs no latch or other fastening; when it is open it lies horizontally to form a temporary shelf. The oven can be affixed to the wall or provided with a stand for the bench. It is patented by 8. Christ and Co. of Berlin. F. H. L. A New Weighing-out Balance. F. Mach. (Chem. Zed. 1901 xxv. 1139.)-This apparatus has been specially designed to economize time in the weighing off of the same quantity of material for analysis, especially when the same watch-glass etc., is always used.It includes three special features the beam is placed end-on in the case; the beam is a "steel-yard," the lengths of its two portions having the ratio 10 1; and the arresting gear is auto-matic. The rear pan carries the weight, which represents (ten times) the net quan-tity of substance the receptacle at the top of the stirrup being intended to hold the counterpoise of the watch-glass. The arresting gear of the beam is so arranged that it carries the rear pan with counter-poise and weight; and only when one-tenth or more of the substance which has to be weighed is put into the watch-glass Both pans have stops The delicacy of the balance exceeds 1 milligramme per on the front pan does the steel-yard beam come into play.to prevent oscillation. 100 granimes. I t is made by W. Spoerhase of Giessen. F. H. L THE AKALYST. IS:, On the Sensitiveness of a Thermo-regulator. A. W. C. Menzies. (Proc. Chem Soc. xviii. H.)-\Yith:the arrangement described below the temperature of the bath could be kept constant at 18” within a total range of O.OOt3.’ C. The glass horseshoe ” reservoir was of the usual form having a capacity of 390 C.C. and an outer surface of about 650 square centimetres ; the ordinary U-form regulating tube containing mercury was fused on to this reservoir all the tubes containing enclosed liquid being placed in the water of the bath. Toluene being used for the expanding liquid the stopcock closing one limb of the U-tube was lubricated with syrupy phosphoric acid. The bath held 14 litres and W&B of enamelled iron, with no jacket. The stirrer was driven by a small electromotor some of the vibration being communicated to the regulator to aid the free movement of the mercury. The gas-supply was regulated so that the by-pass flame was nearly sufficient to maintain the temperature. A tube of 3.1 millimetres bore was used for che outer limb of the regulator and ordinary unfiltered coal gas was used. For narrower tubes the gas should be filtered and dried. A bore of 1.9 millimetres for the outer limh gare a temperature variation of not more than 0-0025‘. A. G. L