MABERY. — DETERMINATION OP SULPHUR. 3 



site is a furnace of suitable construction to maintain an equal tempera- 

 ture, easily controlled in all the tubes within the furnace, without a 

 great loss of heat by radiation. For this purpose and for Carius 

 analyses in general I have recently had a furnace constructed which 

 differs in certain features from any other 1 have seen, and it shows such 

 a high degree of efficiency that a brief description may not be entirely 

 devoid of interest. The body is of tlie ordinary cylindrical form, 75 cm. 

 long and 25 cm. in diameter, of heavy sheet iron, and it is surrounded 

 by two outer jackets of sheet iron each enclosing a half-inch space, 

 and extending beneath on either side to within 6 cm. of the heating 

 tube ; it is supported upon legs of strap iron three sixteenths of an 

 inch thick and two inches wide, each entirely encircling the body at 

 either end for rigidity. These two air spaces retain the heat so effectu- 

 ally that the hand may be borne on the outside of the furnace when 

 the thermometer within indicates a temperature of 200°. The iron 

 tubes are as usual of gas pipe, with threads at either end with caps 

 easily movable by the fingers. With a small hole in each cap for 

 the escape of gas, these tubes retain all glass in the most violent 

 explosions. When several tubes are in the furnace at the same time a 

 record of them may conveniently be kept by suspending metal tags 

 numbered consecutively from the holes in the caps by means of bent 

 wire. 



Figure 1 shows the arrangement of the outer air spaces with the 

 position of the heating tube. The furnace is heated by means of a 

 gas stove heater 45 cm. in length, with thirty-two 

 gas jets that will burn continuously with a flame 

 2 mm. high, giving a temperature within the fur- 

 nace of less than 60° ; by interposing an asbestos 

 or an iron plate a considerably lower tempera- 

 ture may be maintained. The heating tube is 

 supported on two iron straps bolted to the legs, 

 one at either end of the furnace ; by means of it 

 the heat is very equally distributed with little ' ^^^ l 



waste, and the glass tubes being thus evenly 



heated there is less danger of loss by explosion. A temperature of 

 200° may be obtained within twenty-five minutes after lighting the 

 jets, and it may be maintained with jets fifteen millimeters in height, 

 requiring a small consumption of gas ; the hand may be held without 

 discomfort for some time directly beneath the heater. The variation 

 in temperature at different heights within the furnace is small ; with 

 the thermometer at 275° at the level of the upper tubes, the tempera- 



