W. M. HutcJiings — Further Notes on Fireclays, etc. 165 



These various portions separated were collected by settling into 

 smaller and smaller beakers, and finally, as thick mud, into stoppered 

 bottles. They were mounted for examination by mixing some of 

 the mud with a very little gum-water and painting very thin films 

 on the slides with a camel-hair brush, drying, and covering with 

 balsam and thin covers. With a little care even the finest portions 

 could thus be got so that single flakes and grains could everywhere 

 be examined. 



The three finest portions A, B, C, under the microscope are seen 

 to contain far away the largest portion of the rutlle-needles of the 

 clay. These are exceedingly abundant. The main portion of these 

 finest slimes consists of very minute flakes, the smallest of which, 

 especially in A, can only be seen when examined in water instead 

 of balsam, many of the others being only seen in balsam by 

 lowering the condenser very much. Without specifying anything 

 further, it is safe to say that most, if not all, of this distinctly flaky 

 material is micaceous ; and as A, B, C make up a large part of the 

 portion levigated, this very small micaceous substance is a leading 

 component of the original clay. The larger bits are distinctly seen 

 to have a greenish or yellowish tinge. Not a single bit can be seen 

 which could for a moment be mistaken for biotite. In no case is 

 any bit seen which contains rutile ; the two minerals are here quite 

 separate. 



Micaceous ilmenite in small flakes, and little plates and grains 

 of epidote, are rather abundant, also a good deal of matter too minute 

 for any sort of identification. I cannot make out anything that 

 could be safely referred to "Kaoline." 



In the next grades, D and E, we of course get among larger- 

 grained material, and here a considerable number of flakes are 

 seen more or less full of rutile-needles. It was such flakes which 

 I was specially anxious to isolate. 



The first thing to remark about them is, that though they vary 

 a good deal in size, the upward limit is pretty sharply marked off 

 against the flakes which do not contain rutile ; and when the next 

 coarser grades of levigated material, F and G, are examined, this is 

 again strongly emphasized. The number of rutiliferous flakes is 

 much less than in D and E, and those present are largely due to 

 the carrying over of one grade into another; — to the inevitable im- 

 perfection of the separation. 



Considering then the whole of the rutiliferous flakes in D, E, F, G, 

 those over xoVoth of an inch in largest diameter are rare, those 

 reaching to that size are not a large proportion ; the fairly average 

 size of what might be called the larger flakes being about x-3Voth 

 of an inch across. From this downwards there are all sizes till 

 a lower limit is reached, beyond which, as in A, B, and C, no 

 contained rutile is seen. 



If the flakes are studied in detail, it is soon seen that only some 

 of the smaller ones are single flakes at all. Every lai'ger one is 

 seen, by its extinctions, to be an aggregate of more or less numerous 

 smaller flakes overlapping one another, and with different optical 



