1^6 



SCIENCE. 



[Vol. XXII. No. 556 



dish, the gray and the white. Do it with him many times, 

 but each time he will do it more and more himself, till he 

 accomplishes it alone. Should any jsebble have a hole in 

 it, or any special feature, his eye and finger will be sure 

 to find it, and an exclamation will burst forth: "See!" He 

 has discovered something. He now looks for more, like, 

 or similar to it. 



Next, teach him to select them according to lustre, if in 

 a vicinity where micaceous or other sx)ecially lustrous 

 rocks are frequent. If not, as a sjjecial privilege, let him 

 wet some in a hoivl of water while the others are dry. The 

 difference he quickly sees, and next time, if no water is 

 at hand, he will be more than apt to wet them with his 

 tongue, and exclaim again " See ! " his tone and look indi- 

 cating that he recognizes an effect upon the stone like that 

 produced before by the water. Here he has reallj'^ learned 

 that one general agent, under two forms, from two differ- 

 ent sources may produce a similar effect. As to kinds of 

 lustre, he may be readily trained to recognize pearly, like 

 the inside of the shell on the mantel, and glassy; also that 

 the absence of lustre is dull. Of degrees, he can compre- 

 hend shining and glistening, and learn the words as well. 

 A child does not need such short words as we often think. 

 He delights in mastering a " big word," if only for the 

 protracted sound, but if it conveys a pleasant thought, his 

 interest is greatly intensified. 



Next, teach hardness by rubbing two stones together, 

 and by letting him try to scratch them; first with a nail, 

 and second with a sharp-edged piece of quartz ov flint. He 

 can make perhaps three piles — those soft, easily scratched 

 with anything; those harder, only scratched with the nail 

 and quartz, and those hardest, not scratched by the nail, 

 but by the quartz. These distinctions are crude, but real, 

 to the child thart recognizes them. 



What has been thus pursued from day to day in the 

 realm of stones, if the mother or kindergartner is wise, 

 should have been carried on also with plants, insects, and 

 birds, even some lessons on the "twinkling stars." Of 

 these, botany, zoology, and astronomy, we do not now 

 speak, but, be it remembered, that no single science at 

 once bears as strong a relation to, and is so dejoendent 

 upon, a knowledge of botany, biology, chemistry, mineral- 

 ogy, physics and astronomy, as is geology. It emphati- 

 cally furnishes a foundation for them, and in turn must 

 look to them for the interj)retation of its data. 



By the time a child is of ordinary' school age, under 

 such a course of observation, comparison and generaliza- 

 tion as the foregoing would suggest, he has formed a 

 habit of being interested in everything about him. If he is a 

 city child, he can have learned all here outlined, or its 

 equivalent; and if a country child, even more, for he is 

 constantly in direct communication with Nature's open 

 album of new and beautiful objects for observation and 

 subjects for reflection. 



Continuing our study of stones, we will try the action 

 of water as a solvent. The teacher should place in the 

 pupil's way some varieties, as rock salt, or a hard lump of 

 common salt, which are quickly soluble, alum, not as quickly; 

 a rusty nail that will color the water in a few hours, and 

 the child's own quartz pebbles, insoluble. Call attention 

 to the different actions. With the salt a lesson on satu- 

 rated solutions may be given. Having shown the effect of 

 water, try acids — strong vinegar or hydrochloric acid — 

 upon various stones. Some are unaffected, some hiss a 

 little, some boil violently. Can you see anything jsassing 

 off? No. Can you hear anything? Yes; there is a bub- 

 bling. What do j'ou see ? The bursting of the bubbles. 

 Why do they burst? An invisible gas is jjassing off. 

 Have you ever seen anything else boil like that in a bottle 

 or a glass ? Some pupil will suggest " beer " or " soda- 

 water." Tes, and the same cause produces both ; this 



unseen gas we call carbonic acid gas. Let the pupils taste 

 a little cooled, boiled water, and some fresh, hard, well 

 water. One tastes flat, the other good. The same thing 

 that escaped from the stone, beer and soda water, gives, 

 in the main, the difference of taste between these two 

 waters, viz. : carbonic acid gas. Try more stones with the 

 acid. Some hiss, some do not. All that do, have this gas 

 in them, and are called carbonates. Try the acid again on 

 a carbonate. It boils; continue pouring it slowly till boil- 

 ing ceases. Note the effect; the stone has turned to sand- 

 like particles. Take another carbonate, pour on acid; it 

 boils. After a moment pour on some aqua ammonia, the 

 boiling ceases ; pour on more, the stone does not crum- 

 ble. Take a third carbonate; pour on ammonia only. 

 There is no apparent effect. In the first case the stone 

 crumbled ; in the second, the crumbling was checked, 

 and in the third, there was no change. Evidently some- 

 thing holds the grains together. What? Some child will 

 say '• that gas that blew away." What is it called ? What 

 are all such stones called ? Drill on this thoroughly. Il- 

 lustrate solubility and carbonates also by baking soda and 

 cream of tartar. Dissolve a little of each in tumblers of 

 water. Let the pupils taste both in the dry powder. 

 One, soda, is a brackish sweet; the other, tartar-, is a defi.- 

 nite sour. Pour part of the soda solution into the tartar 

 tumbler ; boiling or effervescence is instantaneous. Taste 

 the tartar water now. Almost sweet f What has been 

 given off to produce this change ? Pour the rest of the 

 soda into some sour milk. It, too, effervesces. Taste it. 

 It is sweetened. The sour substances are acids. This ele- 

 ment that sweetens them is an alkali. Ammonia is another 

 alkali. Most alkalies are odorless, and all, if strong, will 

 burn the skin severely. So children should never taste 

 nor play with things in bottles without permission. Give 

 some tiny experiments with heat. Throw several stones 

 into a hot fire. Perhaps some swell up, some grow porous 

 quite rapidly, others more sloioly, and some are unchanged. 

 Some change color, and some discolor the flame nearest 

 them — making it yellower. Tell the pupils the explana- 

 tion of this will come later, but because heat does 

 this sometimes, it is used as a test. As far as pos- 

 sible, always use the children's own stones, and let them, 

 in sections, do the work after you. There will be a little 

 rivalry as to which can do it best and quickest. They will 

 not weary though they see the same thing performed many 

 times. If certain ones are peculiarly apt, let them, at your 

 order, perform the exjjeriment for the lirst time. Among 

 the children's fragments there will be a large amount of 

 rubbish. From time to time the teacher can propose '•' to 

 assort the collections," and casually remark : " So many 

 of these are so nearly alike, which are the most perfect of 

 their kind ? Let us lay such aside, and put the rest in a 

 reference pile for a time of need." The plan is readily 

 accepted, the " collections " greatly reduced, and the ref- 

 use piled in a corner out of doors, to gradually scatter. 



No lessons will be more-acceptable to the pupils than 

 those oi erosion and sedimentation, taught by calling atten- 

 tion to the water in the streets and gutters after a gentle 

 rain, and after a heavy one, a short one and a protracted 

 one. They will readily see its assorting effect. They will 

 notice the little terraces made, and that the form of these 

 — their comparative width and height — depends uj)on the 

 velocity as well as amount of water flowing along. Note 

 how they narrow and deepen when passing under cross- 

 walks, and that the current is swifter. Having noted 

 these things, call attention to any ravines, or creeks, or 

 the river and its bank. Show that when a creek widens, 

 the edges, on either side, are apt to be marshy. Why ? 

 Notice the different appearances of the bottom. If g'rav- 

 elly, is it clean or dirty ? Why ? Some pupil goes too 

 near the edge, and the laank caves off. Why? A shrub 



