€i)e ^o))ular Science ^ttas 



AND 



BOSTON JOURNAL OF CHEMISTRY. 



Volume XXIII. 



BOSTON, APRIL, 1889. 



Number 



CONTENTS. 



Familiar Science. — Simple Scientific Experi- 

 ments 49 



The Science of llie Ice-Pitcher 49 



Evolution 50 



Petroleum and Natural Gas 51 



To Which Kingdom do They Belong? ... 52 



Scientific Brevities 53 



Practical Chemistry and the Arts. — The 



Constituents of Drinking Water. Part II. 53 



The Chemical Nature of Assimilation ... 54 



The Incineration ol Organic Matter ... 54 



A Double-Pointed Nail 54 



Laboratory Notes 54 



Home, Farm and Garden. — Whata Leaf Does 55 



Trees in Winter 55 



Selected Recipes 56 



Gleanings 56 



Editorial. — The Transformations of Energy . 57 



A Photograph of the Total Solar Eclipse . . 58 



Paris Letter 58 



Meteorology for February, with Review of 



the Winter 59 



Astronomical Phenomena for April .... 59 



Zircon 60 



Questions and .\nswers 60 



Literary Notes 60 



Medicine and Pharmacy. — Strophanthus . . 61 



Two Noted Examples of Q^iackery .... 61 



Monthly Summary of Medical Progress . . (>2 



The Phonograph in Physical Diagnosis . . 63 



Obituary 64 



Publisher's Column 64 



Baiijiliar Science. 



SIMPLE SCIENTIFIC EXPERIMENTS. 



A cuRiou.s experiment, illustrating a law of 

 hydrostatic pressure, can be performed by 

 cutting an edge upon tlie ends of two corks, 

 placing them in the necks of bottles, and bal- 

 ancing two knives upon them in such a way 

 that they will just support a glass of water. 

 After a few trials this can be easily accom- 

 plished. Then attach a coin, or any small, 

 heavy object, to a string, and, holding it in the 

 hand, carefully lower it into the liquid. Al- 

 though there is apparently no weight added 

 to the glass of water, yet it will immediately 

 sink down, the suppoiting knives tinning 

 upon the corks like the beam of a scale. Lift 

 the coin from the water and the glass will rise 

 again, returning to its former position, and by 

 the proper manipulation of the coin, the glass 

 can be made to dance up and down at will. 



The explanation of this simple experiment 

 is not as easy as it might seem. It is really 

 an illustration of the upward pressure of 

 liquids. When the coin is dipped into the 



water it displaces an amount equal to its own 

 bulk, and is buoyed up by a force equal to 

 the weight of that bulk of water. This up- 

 ward pressure reacting against the bottom of 

 the glass, forces it downwards, the same as if 

 an additional amount of water, equal in bulk 

 to the coin, had been poured into the glass, 

 thus increasing its weight. We can readily 



of scales may be substituted for the arrang- 

 ment of knives and bottles, figured above, if 

 desired. 



Take a bottle and place a cork over the 

 mouth. The cork must be sufficiently large 

 to rest lightly upon it, without falling into the 

 neck. Snap the neck of the bottle sharply 

 with the thumb and finger, and the cork will 

 fall from the bottle towards the hand giving 

 the blow, and not away from it as might be 

 expected. This effect is due to the principle 

 of inertia, the quick blow forcing, as it were, 

 the bottle away from the cork, before the mo- 

 tion can be transmitted to the cork itself. 



Few persons will be able to perform this 

 experiment satisfactorily the first time, as the 

 instinctive fear of breaking the bottle or 

 injuring the fingers, prevents one from giving 

 a sufficiently powerful blow, in spite of all 

 eftbrts to the contrary. 



The cuts illustrating these experiments are 

 reproduced from La Nature. 



Fig. I. 



understand that if a piece of wood, or any sub- 

 stance that floats on water, were placed in the 

 glass, the weight of the whole would be in- 

 creased, and a- precisely similar efiect is pro- 

 duced when an object that would otherwise 



Fig. 1. 



sink in the water, is suspended in it, although 

 it does not touch the glass containing it. 

 Any sufficiently delicate balance, or pair 



THE SCIENCE OF THE ICE- 

 PITCHER. 



The exceptionally mild winter this season 

 has not been very favorable to the growth 

 and harvesting of the New England ice crop, 

 which, in inanv localities, is more important 

 than the product of the land in the summer. 

 The seasonable cold of the latter part of the 

 winter, however, caused the "growth" of a 

 fair crop in most localities, and there is no 

 danger of a scarcity next summer of an arti- 

 cle which has now become almost a necessity 

 of life during hot weather. 



The freezing of water is such a common 

 and familiar phenomenon, that we do not 

 often stop to think of the remarkable eft'ect 

 which a low temperature produces in 

 changing a liquid into a hard, brittle solid, 

 of a diflerent specific gravity, and which, 

 with the exception of being composed of the 

 same chemical elements, is, practically, a 

 new substance. The true nature of this 

 change, which we call a physical one, we 

 cannot fully undei'stand, and it 'may not be 

 going too far to question whethci- the differ- 

 ence between ice and water is altogether 

 independent of the chemical composition, 

 and whether the so-called elementary con- 

 stituents — hydrogen and oxygen — are not 

 individually modified also. This, however, 

 leads us to the question of the true nature of 

 elements, of which at present we have very 

 little knowledge. 



