288 Krewder— Quantitative Determination of Perchlorates. 
sium iodide the perchlorate is so slowly reduced that the 
hydriodic acid escapes before the reduction is completed. In 
order to delay the distillation of hydriodic acid until the per- 
chlorate had been completely reduced, the potassium iodide of 
experiment (8) was introduced ina short tube sealed at one 
end, so that the meta-phosphorie acid could attack it only 
slowly, and the heat quickly raised to about 300° C, but evi- 
dently without advantage. In experiment (4) the iodide was 
introduced in the same way, but the heat was applied gradually 
and more moderately, with considerably improved results. 
TasieE I. 
KOl0, taken, HOPO, used. KI used. KCIO, found. Error. 
germs. em? germs. germs. erms. 
(1) 0°1000 15 5° 0'0741 0°0259 — 
(2) 0°1000 HG LO 0°0844 0:°0156 — 
(3) 0°1000 15 on 0:0364 0'0636— 
(4) 0°1000 10 5 0:09 0:0023 — 
A. complete reduction of the perchlorate evidently necessi- 
tated the means of introducing the iodide in sufficient quantity 
and at will. 
For this purpose the tube serving for the introduction of 
carbon dioxide was enlarged so as to hold the iodide, which 
could then be added to the solution at any time by a manipula- 
tion of the rubber conducting-tube for carbon dioxide, which 
would draw the acid up to the iodide and, retreating, would 
carry back an easily regulated quantity of the latter. 
i TaB_eE II. 
KCl10, taken. KI used. KC1O, found. Error. 
erms. erms. orms. orms. 
( 5) 0°1000 5° 0°'0984 0°:0016— 
( 6) 0°1000 3° 0:0924 0°0076 — 
( 7) 0:0500 2° 0°0508 0:0008-+ 
( 8) 0°0500 ra 0:0479 0°0021— 
( 9) 0°1000 i 0°0977 0°0023— 
(10) 0°'1000 on 0°0925 0°0075— 
(11) 0°1000 3° 0°0999 ~ 0:0001— 
(12) 0°1000 ae 0°0994 0:0006 — 
(13) 0°1000 4° 0°0966 0°0034— 
Table II gives a number of results obtained in this way. 
Experiments (10), (11) and (12) differed from the others only 
in the employment of a bulb pipette instead of the retort: one 
end being bent so as to reach to the receiver and the other cut 
off rather short with a tube ground into it, serving the same 
purpose of come carbon dioxide and holding potassium 
