CHLOKIDE OF MAGNESIUM. 155 



small to justify us in placing much confidence in Mr Tinzmann's 

 results, especially as we have no duplicate experiments, and no 

 results obtained by the application of water alone with which to 

 compare them. Still the reader will see that experiments with 

 the acid may be safely made. 



I would recommend, therefore, that such experiments should 

 be repeated, upon different crops, and that the acid should be 

 applied in different quantities, at different times, and in different 

 states of dilution. Especially, I would suggest, the compara- 

 tive experiments with common salt and other chlorides already 

 described in a preceding section. 



The muriatic acid of the shops varies much in strength. It 

 contains from 20 to nearly 40 per cent of pure acid. The 

 simplest way of approximating to the equivalent weight of the 

 acid, is to add to it the common soda of the shops, or common 

 chalk, little by little, till it ceases to have the slightest acid taste ; 

 the quantity of acid which requires 180 of soda, or 63 of chalk, 

 to produce this effect, is the quantity to be employed against 

 73 of common salt, 70 of chloride of calcium, and so on. (See 

 table of equivalent quantities, chap. v. 8, p. 99.) 



3. Experiments with chloride of magnesium suggested. 



No experiments, that I know of, have yet been made with 

 chloride of magnesium applied alone. As a refuse of our salt- 

 works it can easily be obtained, and, by solution in the smallest 

 possible quantity of water, may be in a great measure freed 

 from the gypsum and common salt with which, in the mother 

 liquor of the salt-pans, it is usually mixed. It should be tried 



1. Alone, in different proportions, (-J-, 1, 1J, &c. cwt. per acre,) 

 applied at different and successive periods, and upon different 

 crops. Potatoes and corn crops may be especially tried. 



2. In comparison with the other chlorides of which I have 

 already spoken in this chapter, and especially with the chloride 

 of calcium. 



3. In comparison with sulphate of magnesia, (Epsom salts.) 

 If its action is beneficial upon any plant, it is desirable to ascer- 

 tain if an equivalent quantity of magnesia in another state of 

 combination will produce an equal or an analogous effect. 



