164 PLUM. 



tions commonly made use of or sold under the names of 

 "waggon-axle" or "railway grease" may probably be of 

 service in showing the ingredients of the ordinary com- 

 positions, and also that some of the additions or special makes, 

 for suitable special machine use, are by no means what can be 

 recommended for spreading at haphazard on living vegetable 

 tissues.* 



Of two kinds of railway or waggon grease mentioned in the 

 work below quoted, one consists essentially of a mixture of a 

 more or less perfectly-formed soap, water, carbonate of soda, 

 and neutral fat, whilst the other is a soap of lime and rosin 

 oil, with or without water. Frazer's axle grease consists of 

 rosin oil of various numbers, saponified with a solution of 

 sal-soda in water and softened lime ; and these two rosin 

 recipes are apparently very similar to a composition used with 

 success at Toddington. 



Some other mixtures are merely of greasy or soapy com- 

 positions ; one is of tallow and palm oil melted together and 

 mixed with soda ; two others are of palm oil and tallow for 

 the foundation, mixed respectively with sperm oil and caustic 

 soda, or with rape-seed oil and soda ; another, the "Austrian 

 railway grease," is of tallow, olive oil and " old grease." 



So far there would be nothing deleterious to bark beyond 

 what injury may occur from grease gradually soaking into the 

 tissues, but a preparation of " axle grease," composed of black 

 oil or petroleum residue, animal grease, powdered rosin added 

 to soda-lye, and salt, would be highly undesirable to smear on 

 unprotected bark. 



I have had notes of Davidson's composition being very 

 serviceable for smearing. 



Guarding the bark. — Where bark is thick and dead on the 

 outside, as on old Apple trees, or where dressing is chosen 

 of some kind which will not sodden into the tree in the heat 

 of the sun, it may (as above mentioned) do no harm if 

 smeared on to the unprotected bark. But where year by year 

 the smear must be kept on for weeks in autumn and winter, 

 and very possibly have to be applied again towards the end of 

 March, to stop the ascent of the spring brood of the Winter 

 Moths, and also the wingless females of the March Moth, 

 some protection is needed. If this is not given the grease 

 will soak into the cells and stop the passage of the sap, and 

 the tree will die. 



At present the simplest and cheapest, and also most suc- 

 cessful plan that I have had notes of is that which was largely 

 used at one time, and very probably still is, at Toddington. 



* See pp. 370-379 of paper on "Lubricants" in 'Workshop Recipes,' by 

 C. W. Warneford Lock, published by E. & T. N. Spon, Charing Cross, Loudon. 



