a E. Mmiroe. on the use of Porous Cones in Filtration. 337 



The cones* are made of very 

 liave an angle of about sixty de_^ 

 following way : 



A section of a seamless rubber tube a, is stretched around the 

 mouth of a funnel h, preferably a Bunsen funnel, allowing a 

 portion of the tube to project above the top. This part will 

 immediately arrange itself at right angles to the top of the ftm- 

 nel ; mto the circle thus formed the cone c, is put. It is then 

 connected with the Bunsen pump. When the cone is moistened 

 and the pressure applied, the rubber band forms an air-tight 

 jomt and the liquid runs through with great rapidity. Before 

 the cones are applied to quantitative work thev must be cai-o- 

 fully washed, first with concentrated chlorhydric acid, then with 

 (hstilled water, dried, and weighed. A small porcelain crucil)le 

 \yas always kept at the balance in which to w^eigh them. With 

 tills apparatus the following results have been obtained. 



A sample of ordinary crystallized potassio-antimonylic 

 t:i Urate gave 



(1) 1-1069 grms. gave -5570 grms. Sb3S3=35-94 pr. ct, Sb. 



(2) 1-6985 " " -8550 " " "=35-96 " " 



]\[ean 35-95.+ 



Mr. W. Lincoln also made an analysis of the same salt by 

 means of the cones, and kindly permits me to use his results. 



(1) -4683 grms. gave -2388 grms. Sb, 83=86-41 pr. ct. Sb. 



(2) -8135 " <■• -4144 " '" =36-38 " " 



In all of these analyses Sb=120. 



The Sb,S, was precipitated in the manner recommended by 

 Sharpies.;}: It is 1 -^ . - ^ ■.•_.. _:.„..i,i — ....i ^... 



this temperature converted 



some time, a brisk current of sulphydri 



tile liquid. The precipitate is then filtered upon 



cone and the whole dried in an air bath at 300". ' 



