14 



GENESEE FARMER. 



Jan. 



Laboratory CoilverGatio 



Principal — Here is a pound of soil which a 

 friend has sent me to see whether it contains any 

 gypsum or not. If it has one part of the sul- j 

 phate of lime in fifteen thousand, Cooper, you i 

 have learned enough of the practical part of Ag- 

 ricultural Chemistry to get out the gypsum and | 

 "weigh it, have you not ? | 



Cooper — Sir, it is taxing one's skill pretty se- 

 verely to separate any mineral in a soil wheie 1 

 100 grains contain less than the one hundredth 

 part of a grain of the substance to be separated ; 

 still by your improved process for conducting 

 these manipulations, I doubt not my ability to 

 extract plaster from soil if the proportion is so 

 small as 1 to 15,000. 



Principal — Well Cooper, tell these new com- 

 ers* how you will proceed, and then take the 

 soil, and work out the result by an actual de- 

 monstration. 



Cooper — I shall take the pound of soil and 

 burn it in a large Hessian crucible to get rid of j 

 the organic matter. Then I shall boil it for half | 

 an hour in three pints of distilled, or rain water, 

 as it comes from the clouds. A grain of gypsum 

 will dissolve in about an ounce of water, so that 

 all there may be in the soil will be dissolved out. 



Principal — Very well, so far ; but you must 

 not forget that the same water which dissolves 

 the sulphate of lime will dissolve also the chlo- 

 ride of calcium, and all salts of potash, soda, 

 magnesia, and iron. How are you to separate 

 the salt called gypsum from all the otliers ? 



Cooper — Gypsum is but sparingly soluble in 

 Avater, requiring 461 parts to dissolve one ; and 

 is absolutely insoluble in proof spirit, or diluted 

 alcohol. The other salts are soluble alike ia 

 veak alcohol and water. Hence, by settling, 

 and filtering the water quite clear in which the 

 soil was boiled, it can be evaporated down to a 

 wine glass full, or a half gill, and then add as 

 much good alcohol as there is of water. What- 

 ever sulphate of lime or gypsum there may be, 

 will be precipitated, and can be collected on a 

 filter, dried and weighed. 



Princijjal — Suppose your gypsum weighs half 

 a grain, what |)er centage of this fertilizer will 

 the soil contain 1 f 



Cooper — In one pound there are 7,680 grains 

 avoirdupois; or 15,360 half grains. One part in 

 15.360 is a fraction less than the 153d part of one 

 per cent. 



Principal — How small weights do you some- 

 times use in making chemical analyses? 



Cooper — The balance is so nicely adjusted that 

 we use weights down to the 100th part of a grain. 



* CooPKR A.NSiN is :i liul, 15 years did, who lias been 

 with the Editor 7 months, und studied Geology, Anatomy 

 and Physiology, and other branches, besides Analytical 

 Chemistry. 



t The speoimcns furnished, did contain a half grain of 

 gypsum, in 8,000 grains of soil, or one part in 1G,000. 



rincipal — In making an analysis of pota- 

 toes, what interesting fact did you discover ? 



Cooper — That rohan potatoes contain 6 per cent 

 more water than mercers, although both grew 

 near together in one field, and were treated 

 alike. The roha^ had 81 per cent and the 

 mercers 75 of water, t 



Principal — In 100 lbs. of rohans how much 

 ash is there 1 



Cooper — Ninety-five one hundredths of a 

 pound. In mercers there is a fraction over 1 lb. 



Principal — How much potash is there in this 

 ash ? 



Cooper — A little over 50 per cent. 



Principal — From some experiments I have 

 made, how much of the substance of a soil is 

 consumed inorganizing 100 pounds of potatoes ? 



Cooper — From three to seven pounds. 



Principal — Upon what data is this important 

 inference founded ? 



Cooper — Upon the facts of weighing the soil 

 well dried, and the sets of potatoes, before plant- 

 ing ; and also the same soil after the crop has 

 grown, and comparing its loss in weight with the 

 gain in the crop. It must be borne in mind that 

 three fourths of tlie weight of ripe potatoes is 

 nothing but water. 



Principal — In organizing carbon and the ele- 

 ments of water into starch, what chemical sub- 

 stance seems to be necessary in potatoes 1 



Cooper — Potash. Potatoes planted in an arti- 

 ficial soil that lacks potash, form very little starch. 



Principal — Here is a quart of spring water, I 

 suspect it contains lime. How will you deter- 

 mine the fact, and its quantity ? 



Cooper — Evaporate it down to one gill in a 

 clean glass vessel, and add a solution of oxalate 

 of ammonia, so long as any precipitate falls. — 

 This is a white powder, the oxalate of lime. It 

 may be collected on a filter, burnt in a platinum 

 capsule with the addition of a few drops of car- 

 bonate of ammonia, when the oxalic acid will be 

 decomposed, and the carbonate of lime formed, 

 which can be weighed to give the amount. 



Principal — W^hen oxalic acid is decom{ 

 by heat, what new compounds are formed ? 



Cooper — Carbonic acid and carbonic oxide. — 

 An atom of oxalic acid contains two atoms of 

 carbon combined with three atoms of oxygen. — 

 One atom of carbon combines with two of oxy- 

 gen to form an atom of carbonic acid ; while 

 one of carbon unites with one of oxygen to 

 make one atom af carbonic oxide. 



Principal — I suspect the spring water I gave 

 you contains a small quantity of common salt in 

 solution. Tell me liow you will test it for that 

 salt, or chloride of sodium ? 



Cooper — By a solution of nitrate of silver. — 

 This is a very delicate test : the chlorine in the 



X My pupils are just beginning to learn to separate starch, 

 albumen, oil, glutine, fibrine, caseine, sugar, &:c., in or- 

 ganic bodies. 



