124 



IRISH GARDEXIXG 



Notes. 



Formalin : Its Nature and Use. 

 A Correspondent asks— -'What is formalin that 

 one hears so much about lately as a disinfectant and 

 fungicide ? " Formalin is the commercial name of a 

 definite mixture of formaldehyde and water. Formal- 

 dehyde is derived from methane or marsh gas which 

 every one has seen escaping in the form of bubbles 

 from stagnant water when stirred. The chemical 

 formula of methane is CH, and of formaldehyde CH.,0. 

 Fornialdehydi is a i^.is which under tlie influence o{ 



llOl si.-l 1.11.-, i.\ iMHII.i.N lo Hk.m.th. 



House-flies lay their eggs in or on organic matter, usuall}- choosing organic 

 material that has begun to decay. Filth and kitchen rubbish offer a very 

 ready breeding medium. This illustration is a reproduction of a photo- 

 graph showing the larva; and pups of the house-fly on old rags taken from 

 an ashpit (natural size). 



[Reproduced by kind permission from the Report ( 

 City of Liverpool Health Committee 1 



cold condenses to a clear fluid that boils at 21° C. below 

 the freezing point of water. This liquid when mixed 

 with water until it forms 40 per cent, of tlie volume 

 gives us the commercial fluid known as " formalin." 

 As a treatment for scab in potatoes nothing better is 

 known than immersing the affected tubers for twenty 

 minutes in a mixture made up in the proportion of half- 

 pint of formalin to twenty-one gallons of water. For- 

 malin can also be used for the suppression of house-flies. 

 These little pests are really a menace to health, and our 

 dwelling-houses ought to be kept as far as possible free 

 of their presence. Filth of all kinds has a peculiar 

 attraction for flies, hence they carry about very un- 

 desirable bacteria on their legs and other parts of their 



bodies. .All foods particularly should be kept aw.iy from 

 flies. Comparative freedom may be secured by the use 

 of a weak solution of formalin placed in saucers about the 

 rooms visited by flies. The strength used may be two 

 teaspoonfuls to a pint of water. The flies are attracted 

 to the fluid, drink, and almost immediately die. 



The " Greening " of "Seed" Potatoes.— Mr. Geo. 

 Massee, in an article in the current number of the journal 

 of the (English) Board of -Agriculture, describes a series 

 of experiments recently carried out at Kew, with the 

 object of ascertaining in what particular manner the 

 "greening" of potatoes intended for "seed" proves 

 benefici al to the grower. As 

 is well known the skin of a 

 potato is of a corky nature, 

 and cork is a substance im- 

 pervious to water, and if thick 

 enough practically impervious 

 10 air as well. The " green- 

 ing" of a potato tuber has the 

 eflect of thickening its skin, 

 and it is to this thickening 

 apparently th.at the resulting 

 advantages of " greening " 

 arise. Because, firstly, the 

 thickened skin prevents loss 

 of water, and secondly, by 



becking g.aseous interchange 

 between the air inside :ind 

 outside of the tuber, the 

 growth of sprouts from the 

 e\-es is considerably lessened. 

 Potatoes kept in the dark 

 until spring develop long, 

 brittle sprouts that are use- 

 loss, because the)' break off 

 -.0 easily, whereas "greened ' 



1 ubers produce only very short 

 sprouts, and these are tough 

 and not liable to break awav. 

 The experiments also show 

 that the best results are ob- 

 tained by "greening" in the 

 autumn immediateh' after 

 lifting. An additional ad- 

 vantage of autumn " green- 

 ing " is that, to a certain 

 extent, it "checks the 

 ravages of winter rot which 



often spreads in a wholesale manner after potatoes 

 are stored, the fungus readily gaining admission through 

 the soft skin of ungreened potatoes." 



Prop.\gating Shrubs. — The past, present, or suc- 

 ceeding month is the best time to propagate flower- 

 ing shrubs from cuttings. Young shoots approaching 

 ripeness (as they ripen they get firmer) should be 

 selected, and the cuttings planted firmly in pots filled 

 with light, sandy loam. The pots should then be 

 placed in a frame tuitil they form roots. The object, of 

 course, of putting ihem in a frame is to check loss of 

 water from the foliage. When they form roots they 

 can replenish tliemselves with water. 



the Habits, &c., of the House-flv, prepared 

 Robert .N'ewstead. A L.S., K.E.S., &c.] 



