236 Intelligence and Miscellaneous Articles. 



sorbed in its passage j and, consequently, the receiving tube, at the 

 close of the process, will be about half full of gas. When the ore is 

 completely dissolved, the last traces of the chlorine are expelled from 

 the flask by muriatic acid gas. In order that the chlorine thus col- 

 lected may be entirely absorbed, the aperture is closed by a ground 

 stopper, or still more conveniently with the finger, and the gas is 

 well agitated until the chlorine is wholly absorbed. As the solution 

 in the inverted tube may become too saturated to dissolve all the 

 chlorine, it is convenient to fill a pipette with pure water, and, with 

 the aid of the mouth, force a current to ascend into the tube, and 

 thereby cause the heavier solution to flow out into the capsule. 



The absorption being complete, the solution of chlorine is intro- 

 duced into a six- or eight-ounce stoppered bottle, and a dilute solution 

 of green vitriol, made, for example, with a hundred grains of the 

 crystallized salt and a pintof water, is added in successive small quan- 

 tities until the odour of chlorine just ceases to be perceptible. The 

 quantity of liquid required for the purpose may be conveniently mea- 

 sured in a tube about sixteen inches long, and three quarters of an 

 inch in diameter, divided into two hundred parts of equal capacity, 

 and supplied with a lip, so that a liquid maybe poured from it without 

 being spilled. In conducting this part of the process, the operator 

 will perceive two odours : at first, the characteristic odour of chlo- 

 rine, accompanied with the peculiar irritation of that gas ; and, sub- 

 sequently, an agreeable, somewhat aromatic odour, unattended with 

 the slightest irritation. The object is, to add exactly so much solution 

 of iron as suffices to destroy the former of these odours, without at- 

 tempting to remove the latter j a point which, with a little practice, 

 may be readily attained. The whole of the iron is thus brought into 

 the state of peroxide. 



The first trial is generally accompanied with some loss of chlorine, 

 and should only be used as a guide to a second and more precise ex- 

 periment. Accordingly, a weighed portion of the same ore is dissolved, 

 and the chlorine collected as before, except that the solution of green 

 vitriol, in quantity rather less than sufficient, is at once introduced 

 into the inverted tube and capsule. A more ready and perfect ab- 

 sorption of the chlorine is thus effected, and the subsequent addition 

 of a small quantity of sulphate of iron suffices for completing the 

 process. 



The principal sources of error in this method are the two following : 

 loss of chlorine, by smelling repeatedly, and exposure to the air 

 when the gas is absorbed by pure water ; and oxidation by the air 

 when the absorption is made directly by means of the solution of iron. 

 The small flask and inverted tube are apt to retain the odour of chlo- 

 rine, and should therefore be rinsed out with the absorbing liquid. It 

 should be remembered, also, that a given quantity of chlorine will 

 emit a more or less distinct odour, accordingly as it is more or less 

 diluted. But by operating always in the same manner, and employ- 

 ing such weights of different ores, that equal quantities of the solution 

 may contain nearly equal quantities of chlorine, it is easy to be inde- 

 pendent of these errors of manipulation by causing them to aftect 



each 



