32 



SCIENCE. 



[N. S. Vol. XIV. No. 340. 



extent. One examined by the writer contained 

 9.37 per cent, of this element. 



In our experiments in water, sand and soil 

 cultures covering a great many trials we found 

 that magnesia in a soluble form in very small 

 amounts was, in the absence of lime, very toxic 

 to plants. By the addition of lime in a soluble 

 form in amount eqtial to or in slight excess of 

 the magnesia the poisonous effect of the latter 

 was eliminated. The plant was even -enabled 

 to withstand any bad effects from a greatly in- 

 creased amount of magnesia, provided^the lime 

 was also increased in an equal or greater de- 

 gree. 



While the addition of other salts to the mag- 

 nesia in the culture solutions variously affected 

 the toxicity, in no case as far as tested did it 

 have any degree of action comparable with that 

 of the lime salts. 



In sand cultures in which the lime and mag- 

 nesium salts were applied as nitrates the plants 

 made the better growth where the lime was 

 slightly in excess of the magnesia. With lime 

 greatly in excess there was apparently a star- 

 vation of the plant, it making a straggling 

 growth for awhile. With the magnesium in 

 excess the plant soon succumbed, and in mod- 

 erate excess made a slow and unwholesome 

 growth. 



In soil cultures in which magnesium carbon- 

 ate had been added, calcium carbonate was 

 not efficient in overcoming the noxious influ- 

 ence of the magnesia. This was undoubtedly 

 due to the less solubility of the calcium carbo- 

 nate in comparison with the magnesium carbo- 

 nate. By the addition of calcium sulphate the 

 toxicity of the'Jmagnesia was readily overcome. 



In the practical application of lime for its 

 physiological effect the process could be more 

 intelligently carried on where the amount of 

 soluble magnesia and lime already present, 

 i. e., the portion immediately available to 

 plants, is known. However, the danger lies 

 in under- rather than in over-liming. In a soil 

 containing CaO 0.144 per cent, and MgO 0.144 

 per cent, soluble in 1.115 per cent, of hydro- 

 chloric acid the addition of 0.8 per cent, of 

 gypsum, and again of 0.8 per cent, of gypsum 

 and 0.2 per cent, of magnesium carbonate, pro- 

 duced plants similar to those in the natural 



soil. With the addition of gypsum 0.2 per 

 cent, and magnesium carbonate 0.68 per cent, 

 the plants made a very slow and spindling 

 growth, too much so for profitable crops. 



In liming soils for the physiological effect the 

 sulphate is, among the more soluble forms, the 

 best available. Where a large amount is to be 

 added on account of a high magnesia content of 

 the soil it is better to add small portions yearly, 

 as has been pointed out. However, the proc- 

 ess should be repeated until the lime content of 

 the soil is made to equal the total magnesia 

 content. 



As stated by Wheeler in his work on Rhode 

 Island soils, calcium carbonate is the best form 

 of lime for overcoming an acid reaction. In 

 applying it for this or any other purpose care 

 should be taken that magnesian limestone be 

 not used unless the soil is also deficient in 

 magnesia. Again in the continued application 

 of crude potash salts the lime and magnesian 

 content of the soil should be known. In case 

 there is a deficiencj' of lime in the soil the addi- 

 tion of gypsum should also be made in some ex- 

 cess of the magnesia contained in the fertil- 

 izers. 



D. W. May. 



U. S. Depaetment of 

 Agriculture. 



QUOTATIONS. 

 INDUSTRY AND RESEARCH. 



Lord George Hamilton has written to Sir 

 Alfi-ed Hickman, M.P., ex-president of the 

 British Iron Trade Association, explaining why 

 certain contracts were placed by Indian railway 

 companies with American firms. In the course 

 of his remarks he says : "You seem to think 

 that orders have only gone abroad because 

 those who gave them did not understand their 

 business. I wish that it were so. The compe- 

 tition we have to face is founded on something 

 much more formidable and substantial. Chem- 

 ical research, concentration of capital, thorough 

 technical education, improved industrial organi- 

 zation have made in recent years greater ad- 

 vance in America than here ; it is with the prod- 

 uct of these combinations and not with the 

 assumed stupidity of Indian officials that the 

 British engineer has to contend." Sir Alfred 



