124 COXSIDERATIONS OF SOUS. 



which is soft and friable to the touch when dry, but unctuous and 

 somewhat adhesive, when in a moist state. The composition of 

 loams is almost infinitely various ; and it would be in vain to 

 attempt to give an accurate description of their ingredients, without 

 entering upon a series of chemical analyses. Good loam, how- 

 ever, fit for every purpose of the garden, the flower-border, the 

 forcing departments, and the greenhouse, contains a very predomi- 

 nant portion of fine sand, some soft siliceous earth, a very few 

 parts (say 2 to 5) out of the hundred of carbonate of lime, from 

 3 to 15 per cent, of the matter of pure clay (alumina), and a 

 varying proportion of iron, more or less oxidated, which commu- 

 nicates the several shades of light, or deeper brown, or red. There 

 is, however, a species of earth much in request, which is subject 

 to lamentable confusion of terms ; I allude to the peat, bog-earth, 

 or heath-soil, of which perpetual mention is made by Horticultural 

 writers. 



At the commencement of the present century, when the culti- 

 vation of plants began to assume general importance, the term 

 bog-earth was always employed by nurserymen to express that 

 black or deep-brown soil which is found on the surface of moors, 

 or commons, where wild heath prevails and flourishes. This earth 

 abounds in pure white sand, to the extent, perhaps, of 85 or 90 

 per cent. ; it contains black, vegetable, decomposed and fibrous 

 matters, and a little protoxide of iron. By burning, the carbona- 

 ceous matter is destroyed ; and then the sand, tinted by the iron, 

 now more oxidised and red, becomes manifest. Bog earth was an 

 incorrect term for such an earth ; but being in general use, it was 

 so far definite. The word peat has, of late years, been substi- 

 tuted ; but real peat is the soft pulpy matter dug out, at various 

 depths, from bogs or turbaries ; it contains little sand, but a great 

 proportion of decaying vegetable matter, some alumina, and iron. 

 In this earth few plants will thrive well, but occasionally one may 

 be found, as, for instance, Thunbergia alala, which thrives with 

 exceeding luxuriance in it. Writers, however, in nine cases out 

 of ten, mean, when they employ the word peat, to express the 

 surface earth of heaths, and not the binding, heavy soil of the 

 peat-bog. Heath mould, therefore, ought always to be the term 

 employed when the writer means to express a light earth, abound- 

 ing with white sand and vegetable fibrous matter ; that, wherein 



