CONCLUSION. 31 



acid has been added. This slime is phiced inside a suitabk^ wooden 

 vessel and a current of electricity is j^assed through it. The alkali 

 set free by the action of the acid is carried away by the electric cur- 

 rent, while the acid appears to be used over and over a on in. Finally, 

 by combining the acid and alkaline products, a material is obtained 

 in which the potash which has been set free is soluble and available. 

 It is hoped that further investigation will result in some method 

 based on these principles for making the vast quantities of potash 

 contained in feldspathic rocks completely available. 



CONCLUSION. 



A careful reading of the foregoing pages will show that no claim 

 has been made that ground feldspar is an efficient substitute, under 

 all circumstances, for potash salts. The etTort has been to present 

 all the evidence wdiich could be collected, both for and against the use 

 of ground feldspar as a fertilizer. The question is still open, and 

 systematic and long-continued experimentation is the onl}^ possible 

 method of obtaining conclusive informatitm on the subject. The evi- 

 dence so far obtained appears to indicate that under certain condi- 

 tions and with certain crops feldspar can be made useful if it is 

 ground sufficiently fine. On the other hand, it is highly ])r()bable 

 that under other conditions the addition of ground feldspar to the 

 land would be a useless waste of money. At the present stage of the 

 investigation it would be extremely unwise for anyone to attempt to 

 use ground rock, except on an experimental scale that would not 

 entail great financial loss. 



The subject must be approached conservatively, with due regard to 

 business economy. Sensationalism and exaggeration invariably do 

 harm. It is extremely unlikely that ground rock will ever entirely 

 displace the use of potash salts, for its availability must inevitably 

 depend upon many modifying conditions, such as the nature of the 

 soil, the amount of moisture present, the character of the other fer- 

 tilizers used, and the varying root action of different crops. With* 

 tobacco the results so far obtained have been encouraging, but it is 

 possible that this plant, which is a voracious feeder, can make use of 

 the potash in fine-ground feldspar to a greater extent than other fast- 

 growing crops, such as potatoes and the cereals, some of which mature 

 in practically sixty days and must therefore find their plant food in 

 a highly available condition. 



104 



