MR. K. D. LONGE ON THE FORMATION OK FLINTS IN CHALK. 149 
I had a notion previously that Hints grew or had grown bv the 
accretion of silica from the chalk, and I set about getting further 
information on the subject. 
I paid a visit to the Whitlingham pit, and collected some 
fragments of large flints covered with a white coating, as well as 
some of the smaller whole flints. 
It occurred to me that if these forms were flint in an early stage 
of growth they would be represented by still smaller forms, and 
I soon learnt from the workmen that they often met with small 
nodules, apparently chalk, but which contained in the interior 
a small mass of black material like flint ; and they had no 
difficulty in finding for me some half dozen of these nodules. 
Upon scraping off the white powder which forms the outside of 
the nodules I found that the black material in the interior was 
a small mass of flint like that of the larger nodules, and that 
these smaller forms only differed from the larger in the small 
proportion which the flint in the interior bore to the white 
powdery coating with which it was enveloped. 
Having satisfied myself, by a process of examination which 
I shall explain shortly, what these nodules were, I sent a specimen 
of what I called an “Embryo” or “ Baby” flint to Professor Sollas. 
He kindly replied, thanking me for my specimen, and informed 
me that “ They are clearly what you suppose, incompletely formed 
flint.” 
Supported by this authoritative opinion as to the nature of my 
“baby” flint, I proceeded with my enquiry as to the relation 
between the black vitreous flint with the white powder in which 
it was embedded. Upon examining several specimens of small 
and large nodules, under an application of hydrochloric and 
hydrofluoric acids, the connection between the white coating and 
the black vitreous mass in the interior was very apparent. 
The outer part of the nodules effervesced freely to hydrochloric 
acid and was evidently chalk, but as this acid was applied to the 
inner parts the effervescence gradually became less, and for a con- 
siderable thickness round the little flint in the interior the material 
did not effervesce at all. 
I then applied hydrofluoric acid to the inner part of the coating ; 
it at once showed slight signs of effervescence, and upon scraping 
off some of it and putting it into a glass tube with this acid it 
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