<i6 FARM BUILDINGS. 6. 



Exp. 4. Cement of Pickering Castle: 

 taken from z fragment in the north-weft cor- 

 ner of the ditch. 



In genera! appearance fotnewhat refembling 

 the lafl noticed fpccimcn •, but in contexturt 

 very different. The cruft of the outer fur- 

 face, which has been expofed to the influ* 

 cnce of the atmofphere, probably, during 

 many centuries, has acquired ahnoft the 

 hardnefs of limedone : nor is any part of It 

 to be broken with the fingers : neverthelefs, 

 this fpecimen, alfo, is full of liimps of un- 

 mixed lime ; fome of them the fize of fmall 

 hazel nuts ; and at the time I took the fpeci- 

 men (the feafon wet), as foftas butter j when 

 dry they are of the confiftency of very foft 

 chalk. 



One hundred grains of this fpecimen yield 

 fifteen grains of air. 



8 grains of fragments, 



1 2 coarfe fand, 



^6 fine fand, 



3 of a fizelikc matter, 



45 chalk. 



104 grains. 



Obs. 



