14 HOT SPRINGS, ARKANSAS. 



distilled water. The amount of water actually titrated was found by 

 substracting the sum of iodine, starch solution, and distilled water 

 from 500 c. e. As an excess of iodine solution was required to produce 

 the blue color a correction was applied by making 5 c. c. of starch solu- 

 tion up to 500 c. c. with distilled water and adding y- iodine until the 



color of the solution was just as blue as that in the actual determina- 

 tion. This figure substracted from the first figure would give the 



number of c. c. of ^ iodine used by the hydrogen sulphide. In every 



case tried the correction was just equal to the original figure, and in 

 neither of the other tests was hydrogen sulphide found to be present in 

 any of the springs. 



Nitrogen and oxygen were determined by making use of the 

 Tiemann and Preusse modification of Reichhardt's apparatus, the des- 

 cription of which is here taken from Hempel's Gas Analysis (trans- 

 lated by L. M. Dennis, Cornell University): 



This consists of two flasks A and B (Fig. I) each of about 1 liter capacity and con- 

 nected by tubes with the gas collector C. The flask A is fitted with a perforated rubber 

 stopper in which is inserted the glass tube a bent at a right angle and ending flush with 

 the lower surface of the stopper; a is joined by a piece of rubber tubing to the tube 

 be, which in turn connects with the gas collector C. C is held by a clamp, has a dia- 

 meter of 30 mm., is about 560 mm. long, and at the upper end is drawn out to a short, 

 narrow tube, which can be closed with the rubber tube and pinchcock g. In the 

 lower end of C is a rubber stopper with two holes through one of which the tube be, 

 projecting about 2S0 mm. into C, is inserted. Through the other opening passes the 

 tube d, which extends only slightly beyond the stopper and connects C with the flask 

 B. B has a double bore rubber stopper carrying the tubes e, and /; e ends about 10 

 mm. above the bottom of the flask and above the stopper it is bent at a right angle 

 and is connected with d. The tube/, which need not project below the stopper, car- 

 ries a thin rubber tube X about 1 meter in length and provided with a mouthpiece. 

 A pinchcock for closing the rubber between a and b is also needed. 



The apparatus thus arranged is made ready for a determination by filling the flask 

 B somewhat more than half full of boiled, distilled water and removing the flask 

 A by slipping the tube a out of the rubber connection; then by blowing into the 

 rubber tube X, water is driven over from the flask B into the gas collector C and the 

 adjoining tubes until the air is wholly displaced. The rubber tubes at b and g are 

 now closed with pinchcocks. The flask A is then filled to the brim with distilled 

 water, the stopper is inserted, water being thereby driven into the tube a and the 

 flask is again connected with b, the pinchcock being opened. 



The water in B is now heated to gentle boiling, and that in A is allowed to boil 

 somewhat more rapidly. The absorbed air is thus driven out and the gases dis- 

 solved in the water which is in A and C collect in the upper part of C from which 

 they are removed by occasionally' opening the pinchcock at g and blowing into the 

 rubber tube X. 



When upon cooling the apparatus, the gases which have collected disappear, the 

 heating of the flask A is discontinued, the pinchcock between a and b is closed and 

 A is disconnected and emptied. The water in C and B is now entirely free from 

 absorbed gases and air can not enter from without, because the liquid in B is kept 

 continually boiling. The apparatus is now ready for a determination, which is made 

 as follows: The cooled flask A, whose capacity has been previously determined, is 

 filled with the water to be examined and the stopper is pressed in so far that the air 

 in the tube a is completely driven out. a is then connected with b, care being taken 

 that in so doing no air bubbles are inclosed. The pinchcock between a and // is 

 opened and the w 7 ater in A is heated to gentle boiling. The dissolved gases are 

 hereby driven over into the gas collector C. Steam is formed at the same time. The 

 heating of the flask A must be so regulated that the gas and steam evolved never 

 drive out more than half the liquid in C, otherwise there is danger of gas bubbles 

 entering the tubes d and e and thus escaping. 



After heating for about twenty minutes the flame under A is removed. In a few 

 minutes the steam in A and C condenses, and water passes from B to C and A. If 

 a gas bubble is observed in A which will not disappear when the neck of A is cooled 



