CERTAIN USEFUL ANALYSES. 195 



carbonate, or in combination with carbonic aciii, that 

 being the roost common form. Il" it is not present 

 as carbonate, or if this is in so small quantity as not 

 to show any action with acid, there are still means for 

 iti easy ami certain detection. To the solution pre- 

 ▼ioiisly rendered alkaline by ammonia, and already fil- 

 tered to separate iron and alumina, is to be added a lit- 

 tle common oxalic acid. If there be even the smallest 

 weitjhable quantity of lime present, a white powdery 

 pr. . will begin to fall; from the abundance of 



th, [le estimated roughly the proportion of lime 



in the soil. 



All of the above important points, it will be noticed, 

 may be determined without any necessity for expen- 

 sive materials or apparatus, by a person of ordinary 

 intelligence. Easy as these things seem, however, 

 in the description, so many difficulties will be found 

 in practice, as will give the operator some conception 

 of the care and study involved in a complete ami de- 

 tailed analysis; one where it is intended to ensure the 

 greatest possible degree of accuracy. 



I have not mentioned any tests for the presence c^ 

 phosphoric acid, and other of the less abundant sul>> 

 5tan<vs; because their detection and separation is so 

 tliili' lilt, that the inexperienced beginner would only 

 run into every description of error while looking for 

 them. 



It is not a hard matter for th- at 



the probable vahu* of a marl, w i le 



•ii'LMte of accuracy. A weightii portion ii 

 takiii, and diluttni muriatic acid adde«l fr<>i<i 

 time, until all etrer>'escence has ceaMnl. I ire 



is then Imiled, or at least well heated, uiki luiuwa 

 upon a filter. The insoluble rf>si<lu«> which remiM 

 ttpon the filter, must be \\ " ' i--*!, 



and wcii;ht'tl : this is < *>• 



tr:i( t(>tl from the original wt-tght taken, will, 



