182 



Effect of Coal Smoke on Plants. 



[May, 



to place with a fair degree of accuracy the nature of the offals 

 sold. It is hoped eventually that millers will agree to classify 

 their offals on a standard basis, as this will give the farmer an 

 accurate idea of the feeding value of any wheat offal whatever 

 its local name may be. 



The Feeding Value of Whole Milk. — A correspondent has 

 written asking that the value of milk based on a price of 8d. 

 a gallon, and a fat content of 3 per cent., may be given in the 

 table. It has therefore been included. 



It will be seen that, at 8d. a gallon, milk is a dear feeding 

 stuff. Its use could only be justified for feeding in special cir- 

 cumstances, as in the case of very young stock, or where local 

 conditions preclude its sale. In the latter case, it would be 

 more profitable to manufacture cheese or butter for sale and to 

 feed the residues rather than to feed the whole milk itself. 



* - ; * * * * * 



Coal smoke and the presence of sulphurous acid in the 

 atmosphere have for long been two of the greatest trials with 



Effect of Coal wn * c h R°y a l Botanic Gardens, Kew, 

 „ „ . have to contend, and the winter conditions 



Smoke on Plants. , j , . , , . , , 



are so bad that it is almost impossible to 



cultivate certain evergreen trees. Winds from the north 

 and north-east almost invariably carry coal smoke to Kew. 

 In summer the smoke may only be noticeable as a slight 

 haze, but in winter it takes the form of dense fog. A fog 

 of a few hours' duration causes the flowers and leaves 

 of many indoor plants to fail, owing to the sulphurous acid in 

 the atmosphere, whilst out of doors everything is covered with 

 a thick deposit of fine greasy soot. This deposit is very notice- 

 able upon water, glass, and the leaves of plants. The breathing 

 pores of leaves become clogged and the plants are enfeebled ; in 

 fact, so disastrous is the dirt to health that it has become 

 impossible to cultivate many of the firs and spruces. 



A temporary exhibit has been arranged in Museum III at 

 Kew, consisting of leaf specimens showing the difference 

 between clean foliage and smoke or soot-laden foliage, and of 

 glass from a greenhouse showing the effect of fog, 



fn order to increase the educational value of the Gardens, it 

 is proposed from time to time to arrange other small exhibits 

 at Kew, of objects of particular interest at the moment. 



