9 



mide is present in the mixture per bushel of the manure treated. The 

 cost of such a mixture is about Id. per bushel, this being materiallv 

 lessened when the increased fertilising value of the treated manure is 

 considered. 



Potassium cyanide, Paris green, arsenic dip and pyridine cannot be 

 recommended "owing to their extremely toxic action. 



A bibliography of seven works is given. 



Phelps (E. B.). Studies on Sodium Salicylate, a new Muscicide, and 

 on the Use of Formaldehyde. — C/. >S. Pxblic. Health Reps., 

 Washington, D.C., xxxi, no. 44, SrdNovember 1916, pp. 3033-3035. 



Among methods of fly destruction suitable for use in households, 

 poisoning seems to possess the fewest disadvantages. In view of the 

 dangerous nature of arsenic, an investigation was made with special 

 reference to the selection of some other substance, which under ordmar}- 

 conditions of use, and of accidental misuse, would not be so dangerous 

 to children, while serving equally well, or better, for the destruction of 

 flies. Only two have been found to possess the requisite properties, 

 viz :— formaldehyde and sodium salicylate. The former, in solutions 

 of various strengths, has been recommended from time to time for this 

 ]3urpose. In the present investigation the best results were obtained 

 with a 1 per cent, solution, or 2| per cent, of the 40 per cent solution, 

 the usual commercial form. This insecticide was found to possess a 

 valuable property in that, whereas at summer temperature it is 

 somewhat less efficient than commercial arsenical preparations, its loss 

 •of efficiency with decreasing temperature is much less and its relative 

 value, therefore, correspondingly greater. During the cooler days of 

 autumn, at which time the greatest difficulty is experienced in keeping 

 the flies out of houses, this preparation compares most favourably 

 with arsenic papers. Sodium salicylate has not, to the author's 

 knowledge, been previously recommended for this purpose. In a 

 I per cent, solution it is slightly less efficient than formaldehyde, but 

 possesses certain marked advantages for household use. It is a less 

 objectionable substance in a concentrated form, is a solid which does 

 not lose its strength, and in the preparation of the solution the exact 

 strength recommended need not be so carefully adhered to. Further- 

 more, it lends itself to the preparation of papers in much the same way 

 as arsenic papers are now prepared. Like formaldehyde, it does not 

 lose efficiency at lower temperatures nearly so rapidly as arsenic. For 

 household use either of these solutions may be prepared by the addition 

 of three teaspoonfuls of either the 40 per cent, solution of formaldehyde 

 or the powdered sodium salicylate to a pint of water. A glass tumbler 

 is nearly filled with the solution, a circular piece of blotting paper, 

 somewhat larger in diameter than the tumbler, is placed over it, and 

 over this an inverted saucer. The whole device is then turned upside 

 down and a match is inserted under the edge of the tumbler to allow 

 access of air. The blotting paper will remain in a moist condition 

 until the entire contents of the tumbler have been used and the strength 

 of the solution will remain uniform. The attractiveness of the bait 

 may be increased by sprinkling a little sugar upon the paper, but 

 this is not advisable where there are young children. 



