CHALK IN SOILS. 115 



rHALK IN SOILS. 



1. Carbonate of lime chalk. Place a 

 small piece of chalk in a saucer and pour 

 upon it a little w/V, which may he strong 

 vinegar, lime juice, or hydrochloric acid. Note 

 how it bubbles up, due to its giving oft* carbon 

 dioxide. Chalk always does this when acted 

 on by an acid, and thus this is a useful test to 

 find out whether a soil contains chalk or not. 

 Repeat the experiment, using small quantities 

 of soil from different places.* From the obser- 

 vations made classify the soils as calcareous 

 and non-calcareous. 



2. If the surrounding district contains 

 examples of both calcareous and non-calcare- 

 ous soils, mark their distribution on a map. 

 For this purpose small samples should be 

 collected, by the pupils, from a number of locali- 

 ties, and examined as a class exercise or as a 

 demonstration by the teacher. A map of the 

 island, or of the district, on a somewhat large 

 scale, may be drawn on stout drawing-paper 

 and hung up in the class-room. Observations 

 on the character of the soil may be recorded, 

 from time to time, by means of colours upon 



* The teacher should provide himself with a collection of 

 soils from different places, taking care to have samples of both 

 calcareous and non-calcareous soils. These samples are prefer- 

 ably kept In bottles. 



