ON THE PROCESSES FOR CLARIFYING LIQUIDS. 233 



This filter may be ufed for many other fluids, particularly 

 ihofe of an aqueous nature, which do not contain potafh or 

 foda in folution. For if they were only (lightly alkaline, the 

 filter would be foon deftroyed, and the filtered liquor would 

 not pofiefs the requifite qualities. 



Linen or cotton cloths, and paper, are commonly ufed for Linen or cotton 

 alkaline liquids, and they fucceed very well, particularly ^°^ t °jj P*P er » 

 when thole fluids are not too concentrated. With regard to applied. 

 carded cotton, it is referved to filter fuch fluids as are of con- 

 fiderable price, or very fcarce. 



This filter is made by introducing carded cotton into the Carded cotton, 

 tube of a glafs funnel, where it is lightly prefled together with 

 a glafs rod fo as to form a kind of Hopper ; after which the 

 fluid intended to be filtered is poured into the funnel. The 

 filtration takes place drop by drop and after the firil drops 

 are feparated, thofe, which follow arc always clear. The ef- 

 fential oils may be very well filtered by this method, without 

 any fear of that lofs which would neceilarily follow if the other 

 filters before fpoken of were ufed. 



The acids, particularly thofe which are concentrated, can Filter of pound- 

 dnly be filtered through pounded glafs ; but care mult be taken ed g » 

 not to ufe this fubftance till after it has been walhed feveral 

 times, firft in a large quantity of water, and afterwards in an 

 acid, in order to deprive it of the earthy fubftance which the 

 acids might diflblve. 



Glafs filters may be very well conftruc"led in a funnel. The how constructed, 

 great art in order that they may produce the effect, 'is to fix in 

 the fir/1 place fome fragments of glafs in the tube, and after- 

 wards to have others which are fmaller, and this procefs muft 

 be continued, coirftantly diminifhing the fize of the fragments 

 until the powder lies to the thicknefs of three or four inches, 

 the laft ftratum of which muft be very finely pulverifed. 



This kind of filter operates fo well, that in lefs than an hour 

 it is polfrble to filter through a funnel of middling fize feveral 

 kilograms of acid. 



Sand is alfo very commonly employed to clarify water for Filtring by (and. 

 domeflic ufes. Sandy fprings are in facltrue filters, of which 

 the effect is more certain, in proportion as the layers of fand 

 are fo difpofed, that the water upon them may be obliged to 

 pafs through the fand fucccilively, and leave thole bodies 

 jvliick injure its tranfparence. 



The 



