ON THE USE OF LIME, MARL, AND SHELL-SAND. 



23 



when undertaken in a proper manner, will give an analytical 

 chemist plenty of work for a number of months. 



The first marl on which I have to report was forwarded to me 

 by Mr. Symes, of Combe, near Sherborne. This marl on analysis 

 was found to contain in 100 parts : 



Moisture and organic matter 5*41 



Oxides of iron and alumina 6*94 



Carbonate of lime 10*55 



magnesia 1*44 



Phosphoric acid trace 



Insoluble silicious matters (chiefly fine sand) . . . . 74'86 



Alkalies and loss '80 



100-00 



It will be observed that this is a sandy marl, i. e. a mixture of 

 some clay with carbonate of lime and much sand. On light 

 soils deficient in lime this marl would produce a beneficial effect, 

 but since it contains so large a proportion of sand and but little 

 lime I doubt the propriety of using it if it has to be carted any 

 distance. At the best it is but a poor sandy marl, which can 

 only do good when used in very large quantities upon light soils 

 quite deficient in lime, or upon heavy land, which is benefited 

 by almost any mechanical ameliorator. 



In the next Table I have grouped together the analyses, made 

 some time ago, of three marls found in the West of England. 



No. I. is a clay marl from Bridgewater. 



No. II. a chalk marl, or malm as it is locally called in 

 Wiltshire. 



No. III. another chalk marl from Gloucestershire. 



No. I. No. IL No. III. 



Water and a little organic matter 3*38 



Finely divided silica (soluble in caustic potash) 17'94 16'710 0'26 



Insoluble silicious matter (fine clay) .. .. 54'89 6'090 



Oxides of iron 8'82) 



Alumina 6'67J 



Lime 1*44 40'757 52-33 



Magnesia 0'92 -825 0'31 



Potash 1'48 traces traces 



Soda T08 traces traces 



Phosphoric acid 0'51 -242 traces 



Sulphuric acid traces 1-546 



Chlorine traces traces traces 



Carbonic acid and loss 2'87 33'050 44'70 



100-00 100-000 100-46 



Marl properly speaking signifies a mixture of clay, carbonate 

 of lime, and sand, with or without organic matter, containing not 

 less than 5 or 6 per cent, of carbonate of lime. 



780 2-86 



