60 THE MINERALS OF THE MIDLANDS. 



ON THE OCCUREENCE OF NATIVE CALCIUM CHLORIDE 



AT GUY'S CLIFFE, WARWICKSHIRE. 



RY JOHN SPILLER, F.C.S. 



lu tlie covirse of a holiday tour throuf^b Warwickshire, made iu 

 the month of September last, I visited the Grounds at Guy's Cliffe, 

 situated on the Avon, about one mile from Warwick Castle. At this 

 point the New Red Sandstone (Keuper) crops out in the form of a low 

 cliff, with grass lawn at the foot sloping down to the Avon ; and at 

 the time of my visit I noticed a black slimy exudation upon several 

 parts of the cliff face, which iu places, and particularly on the river 

 front, presented the appearance of having been bedaubed witli tar. 

 Occasionally it occurred only in patches, but in Guy's Cave and (jther 

 excavated or sheltered positions the walls were uniformly covered 

 with black slime to the height of about Gft.. the top line of demarcation 

 being sometimes very sharply defined, as though dependent upon the 

 porosity of the sandstone strata. The Monks' Cells, at a higher 

 elevation (in the courtyard beliind the house), also showed the same 

 indications, and I leaint by inquiries on the spot that this was the 

 normal condition of the rocks at Guy's Cliffe. 



Desirous of ascertaining tlie composition of this black slime, I 

 scraped off a sample from the face of the rock, and brought away with 

 me likewise a few pieces of the sandstone, on whicli, although 

 occiirring close by, there were apparently no traces of the dark- 

 coloured exudation. Both these substances wei'e submitted to analysis, 

 and I have only to remark that, inasmuch as my sample of the black 

 slimy matter had a few dead leaves aud stalks in it. besides living 

 Algff' hopelessly intermingled, it was impossible to ensure uniformity 

 of composition by depending on the original weights. The analysis 

 had, therefore, to be performed by the system of general (or standard) 

 solution, equal portions being taken for the estimation of the several 

 ingredients, and the ratios deduced from the products severally 

 obtained. Then it was only necessary to add on the water given by a 

 direct determination, in a picked sample, to become possessed of all 

 the data requisite for the calculation of the percentage cjuantities. 



THE EOCK, liUV's CLIFFE. 



A friable, micaceous Sandstone, colour greyish white. Ti'eated for 

 analysis with very dilute hydrochloric acid. The following are the 

 analytical results : — 



Composition in 100 Parts. 

 Sand and mica . . . . . . . . . . ll;Vfi4 



Alumina, ferric oxide, etc. . . . . . . l"2i 



Calcium carbonate . . . . . . . . '200 



Magnesium carbonate . . . . . . . . ■<)() 



Moisture and loss . . . . . . . . . . "-Ki 



100-00 



THE SALINE DEPOSIT, fi U Y ' S CLIFFE. 



Composition in 100 Parts. 



Potassium chloride .. .. .. .. 1*21 



Sodium chloride. . .. .. .. .. llUI-i 



Magnesium chloride . . . . . . . . 3-iSl 



Calcium chloride. . .. .. .. .. "JT'l;") 



Calcium sulphate . . . . . . . . . . 14-5;") 



Calcium nitrate . . . . . . . . . . Trace. 



Water and vegetable extractive matter . . i2'2ij 



10000 



