56 



Scientific Proceedings^ Royal Dublin Society. 



and were left standing in the dariv room in order to allow the precipitates to settle. 

 On the next day the titration of the whole set was finished by dropping in the 

 silver nitrate solution and watching by. the aid of a red lamp for the appearance 

 of a cloud. When no cloud appeared after one minute, a reading was taken. The 

 addition of two drops then produced no further cloud. In the first series the 

 silver nitrate was added from a dropping funnel, which was weighed before and 

 after the experiment, and the volume added was calculated from the specific 

 gravity of the solution. In the second series a one c.c. pipette, graduated in 

 hundredths, and having a small syringe attached to regvilate the dropping, was 

 used. In both cases the volume of one drop was about 0'03 c.c. 



In the first series of experiments the three B samples were titrated first, 

 followed by the two /3 samples. In the second set the B and the j3 samples were 

 alternated. The results of the experiments are tabulated below. The weight of 

 lead chloride was obtained by subtracting the mean weight of the boat before and 

 after the experiment from the weight of the boat and fused chloride. In ISTo. 3 

 of the first series the weight of the boat varied by 0-4 milligram ; and in No. 1 of 

 the second series it varied by 0'5 milligram. Fn all the other experiments the 

 variation in weight did not exceed 0'2 milligram. The final column of each table 

 gives the volume of silver nitrate recj[uired per gram of lead chloride as calculated 

 from the experiments. 



FiEST Sekies. 



200 c.c. of silver nitrate solution added to each from pipette. 

 Specific gravity of silver nitrate solution, 1-005. 



Second Sbuies. 



Wt. of 

 PbCU. 



Vol. of AgNOs 

 solution. 



Vol. of AgNOa 



solution per 



jiiani of 



PbCh. 



(1) Load B, 



(2) Lead /3, 

 (3j Lead B, 

 (4) Lead &, 



grriis. 

 1-08875 



1-0922 



1-09275 



1-09285 



201-36 

 202-25 

 202-06 

 202-31 



c.c. 

 184-94 



l.'5-17 



lSl-9i 



185-12 



