﻿28 



INDIANA UXIVEESITY 



acid remaining to give an opalescence with silver nitrate. All of 

 the hydrochloric acid conlcl probably have been removed by main- 

 taining the temperature somewhat below 135'' for a period of time, 

 bnt this experiment was not tried. This table shows that the hydro- 

 chloric acid is completely volatilized at a temperature of 135°. 



Table I^' 



-Loss OF Peechxobic Acid Durixg the YoEATiLizATioisr of the 

 Hydeochloeic Acid. 



Volume of Cc. of substances added, 



aqueous / ^ 



HCIO4 used. 



40 

 40 

 40 



H,0. 



0 

 50 



HCl (cone. > 



90 



Cram 



of HCIO4 



present. 

 6.97 

 6.97 

 6.97 



HCIO4 lost. 



Crams. Percent. 



0.09 0.13 



0.14 0.20 



0.19 0.27 



The solutions, containing known amounts of perchloric acid 

 and water or hydrochloric acid, were heated upon the hot plate 

 until the temperature reached 135°. The maximum loss of 0.27 

 per cent is so small that it can be neglected in a method of prepara- 

 tion. 



Table V. — AMorxT or Washixc^ Needed to Remove the Perchloeic Acid 

 EEOM THE Sodium Chloride RESiorES. 



The residue was first drained by suction. It was then washed 

 ^^dth five 1 cc. -portions of concentrated hydrochloric acid, again 

 drained by suction, then washed with a second five 1 cc. -portions of 

 acid, and the operation repeated, altogether four times. Each five 

 1 cc. -portions was saved sepa rately and analyzed. 



HCIO4 washed from the 



Cone. HCl used in washing:. residue of NaCl. Crams. 



First, five 1 cc.-portions large anioiints 



Second, five 1 cc.-portions 1.65 



Third, five 1 cc.-portions 0.19 



Fourth, five 1 cc.-portions 0.08 



After washing with twenty 1" cc.-portions of acid. 0.06 gram of 

 sodium perchlorate still remained in the residue. This table shows 

 that ten 1 cc.-portions of concentrated hydrochloric acid is the most 

 economical amoimt to use in washing the residue from 20 grams of 

 sodium perchlorate and 25 cc. of concentrated hydrochloric acid. 



In one experiment 20 grams of barium perchlorate were treated 

 with 60 cc. of hydrochloric acid. The precipitate of barium chlo- 

 ride was very bullr^' and voluminous, entirely filling an ordinary 

 Gooch crucible. The 60 cc. of hydrochloric acid made the residue 

 liquid enough so that it could be poured upon the filter. The yield 



