Hl. W. Wiley—Automatic Filtering Apparatus. 303 
washing fluid, and by the time the first portion has run through 
- are again ready to decant. By other processes filtration 
as to be suspended each time until the supernatant liquid is 
r 
Washing precipitate on filter.—By means of the thumb screw, 
¢, the apparatus can be adjusted to discharge jets of water from 
with force enough to thoroughly stir up the precipitate each 
time, thus greatly facilitating the process. 
aving time.—This is the chief feature of the automatic fil- 
ter. I give below some tabulated data taken from a great 
number of observed filtrations. In all these cases the results 
were as good as those usually obtained by hand and in several 
instances, owing to special care, better. : 
ashing precipitate BaSO, by decantation. 
Adjustment 5 min., filling 3 min., washing 12 min., total 
20 min. Time apparatus at work, 3 h. 15 min. Amount 
wash water, 2 liters 600 am.*. 
- Washing precipitate Fe,O,H,. 
Adjustment apparatus 2 min., filling 3 min., washing 15 min., 
total 20 mi Time, apparatus at work, 2h. 40 min. Amount 
ei 2 lit. 200 em.*. ees 
- Washing precipitate BaCl,. : : 
Adjustment peor filling 2 min., washing 18 min., total 24 
min. Time pparatus at work, 1 h. 40 min. Amount filtrate 
1 — 250 cm.® 
- Washin HH; : 
Adjustment 1 min. filling 1 min., washing 5 min., total 4 
min. Time apparatus at work, 1 h. 50 min. Amount was 
water 525 em.® 
While at work the apparatus requires no attention whatever. 
It can be adjusted so that the height of the liquid in B will not 
vary more than a millimeter. By fitting B with a hot water 
jacket, which can be very easily done, precipitates which easily 
Oxidize can be thoroughly washed and kept at 100° out of con- 
tact with the air. 
e whole cost of the apparatus need not exceed three = 
four dollars, and usually all that will have to be bought is — 
electro-magnet. Other necessary parts will found in the 
rato 
- 
I am indebted to the kindness of Mr. Ed. H. Ketcham of 
Dartmouth College for the accompanying drawing. 
