Vol. XIII. No. 3U. 



THE AGRICULTURAL NEWS. 



155 



anyone had lived in it. The owner, who had built it for his 

 own residence, resorted to naphthalene as a remedy for the 

 infestation. A sufficient quantity of this material was 

 procured to cover the floor of one of the largest rooms some 

 2 or 3 inches deep. The naphthalene was used in 

 succession in the several rooms, halls and passages of the 

 house, being left in each place for twenty-four hours. This 

 treatment freed the house from fleas. 



'More recently, I have read an account of the successful 

 use of this material for removing fleas from kittens. The 

 naphthalene available for the purpose was in the form of the 

 ordinary balls, which were pounded up and the fine powder 

 of naphthalene was rubbed into the fur of the kittens from 

 the tail toward the head. The fleas were said to retreat 

 before the naphthalene, and eventually they were all driven 

 from cover on to the heads of the kittens, where they were 

 captured. 



'For some time it has been rather a puzzle to know what 

 to do for fleas on my dogs. The fox terrier has so much 

 clear white in his coat that I have not liked to use Keating's 

 powder or pyrethrum because of the yellow colour which 

 is often left by these insecticides. Kerosene in any form 

 and whale-oil soap are objectionable on account of their 

 characteristic odours. The ordinary soaps used in washing 

 the dogs bring out the fleas but do not kill them. With 

 these difliculties in mind, I remembertd about naphthalene 

 and resolved to try it. I had on band a small amount 

 of the lumps or "crystals" as this form is sometimes 

 called. This was pounded to a fine powder, almost a dust, 

 and the application was made, the results being most 

 satisfactory. Most of the fleas that came out of the dogs' 

 coats were dead by the time they fell to the paper on which 

 each animal was made to stand for treatment, or they 

 appeared to be so, while the others were much stupified. 



'By using a paper in this way the naphthalene may be 

 taken up and saved for future use. It can be stored in 

 a card board or wooden box, and if the fleas which fall on 

 the paper are simply left in the naphthalene they will be all 

 killed — there is no need to kill them in the ordinary way of 

 catching and crushing. 



'This is a very simple and effective method of freeing 

 dogs from fleas, and it is clean and cheap. A pound of 

 naphthalene will last a long time, the dogs are not affected 

 by it, and it can be applied by anyone.' 



THE SOIL 



THE EFFECT OP HEAT ON HAWAIIAN 



SOILS. 



In the following summary, considerable light is 

 thrown upon the reasons for the beneficial effect which 

 heat has upon the inanganiferous soils of Hawaii. The 

 information is taken from Bulletin No. 80 of the 

 Hawaii Agricultural Experiment Station. This publi- 

 cation should be consulted for further details. 



Twelve ditt'erent soils representing a wide range of 

 types and agricultural conditions were studied with reference 

 to the effects of heating to 100°C., to 'IWC, and to ignition. 

 The solubility of all the mineral constituents except sodium 



was determined, using water and fifth-normal nitric acid as 

 solvents. The effects on the nitrogen compounds were also 

 investigated. 



The results showed considerable variation. Neither the 

 absolute nor the relative solubility of the inorganic con- 

 stituents was affected similarly in all the samples studied. 



On the average, drying at 100°C. was found to bring 

 about an increase in the water soluble manganese, lime, 

 magnesia, phosphoric acid, sulphates, and bicarbonates. At 

 this temperature an increase on the solubility of potash, 

 silica, and alumina was produced in about 50 per cent, of 

 the soils examined, but a decrease was observed in the 

 solubility of these elements in some instances. The solubi- 

 lity of iron was increased in most instances. 



Heating to 250^0. or ignition produced effects on the 

 solubility in water similar to those brought about at 100°(J. 

 but varying in degree, these being sometimes greater, some- 

 times less in intensity than those produced at 100°C. 



The solubility in fifth-normal nitric acid was not greatly 

 aifected by heating to lOO'C., but in some instances heating 

 to 250°C. considerably increased the solubility of alumina, 

 manganese, potash, and phosphoric acid and at the same time 

 effected a reduction in the solubility of lime ana magnesia 

 Upon ignition the solubility of silica, alumina, potash, 

 phosphoric acid and sulphates was increased, while the 

 solubility of lime and magnesia underwent a corresponding 

 decrease. 



The solubility of soils used in aquatic agriculture is 

 abnormally high, but upon drying out these become much 

 less soluble and approach a state similar to that existing in 

 aerated soils. When such soils are heated after drying 

 they seem to undergo changes of the same order as are 

 produced in dry land soils. 



No single factor is sufficient to cover the solubility 

 ertects resulting from heating Hawaiian soils. On the other 

 hand, the subject is very complex and involves many factors. 

 Among the more important of these may be mentioned 

 tlocculation, deoxidation of manganese dioxid, o.xidation, 

 particularly of iron; double decomposition, dehydration, and 

 the attending physical alterations of soil films. iSucli altera- 

 tion would destroy film pressure, thus allowing the solvent to 

 come into more intimate contact with the soil constituents. 

 At the higher temperatures bicarbonates become converted 

 into normal carbonates, thus effectively lowering the solubility 

 of lime and magnesia. 



Nitrates undergo decomposition with heat, a decrease 

 in nitrate content having been found to take place at L50°G'., 

 while at 200° or 250'C. practically total destruction of 

 nitrates took place. 



One of the noteworthy eftects of soil heating is the 

 production of ammonia, which at 200"C. was formed in 

 abnormally large amounts. Soil subjected to heat from 

 brush burned in the field was found to undergo stimulated 

 ammonification after heating. Nitrification, on the other 

 hand, was not restored after the lapse of two months. 



Heating to 200X'. caused a loss of approximately 

 25 per cent, of the total nitrogen. A loss of nitrogen and 

 the ammonia formed by the action of heat came largely from 

 the monamino acid group, while the amids and diamino 

 acid sustained much less loss. 



The results of these studios are believed to throw 

 important light on the subject of soil aeration, and conse- 

 quently have a direct bearing on the practical question of 

 soil management. 



