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AND 



BOSTON JOURNAL OF CHEMISTRY. 



Volume XXII. 



BOSTON, NOVEMBER, 1888. 



Number 11. 



CONTENTS. 



Familiar Science. — Simple Scientific Experiments 159 



The Megjilithic Monuments of C.irna':! 160 



The Tendency of Matter at the Surface of the Earth 160 



The Origin ol the Sneezing Formula 161 



How a Mound was Built 16- 



Scicntlfic Brevities 102 



Practical Chemistrt and the Arts. — Soap 163 



Fast Time on American Railroads 163 



Filtration with Filters of Metallic Felt 164 



How Celluloid is Made 164 



Ballooninir with Natural Gas 164 



Practical Recipes 164 



Industrial Memoranda 164 



Home. Farm, AND Garden. — Edible Mushrooms U!i 



On Pomology 165 



Ancient Horticulture 166 



The Fallacy of "Plain Living" 166 



Selected Hecipes 166 



Editorial. — Organic Chemistry 167 



Meteorology for September, 1888 168 



Astronomical Phenomena for November, 1888 169 



Bowlder Kocks 169 



Questions and Answers 169 



Literary Notes 169 



Medicine and Pharmacy. — The Opium Habit 170 



Monthly Summary of Medical Progress 170 



Whooping-Cough 171 



Medical Memoranda 172 



Publishers' Column 172 



JFamtltar Sctente. 



SIMPLE SCIENTIFIC EXPERIMENTS. 

 The phenomena of the surface tension of 

 liquids are at present receiving much atten- 

 tion from phj'sicists. The subject was full}' 

 described in the July number of the Science 

 News; but we may say briefly that it is now 

 believed that at the surface of every liquid there 

 is a thin film of the same substance, which is 

 in a state of constant tension, like an elastic 

 membi'aiic. A rubber toj* balloon distended 



Fio. 1. 



with water roughly illustrates the conditions 

 present in a drop of that liquid. 



From certain investigations made by Pla- 

 teau and Quincke, it is estimated that the 

 thickness of this film is not more than yjjHjg^j 

 of an inch. The tension of the film varies 

 with different liquids ; for water it is about 

 two and three-quarters grains for ever}' inch 

 of length, for alcohol a little less than one 



grain, and for ether only about three-quarters 

 of a grain. The following experiments, illus- 

 trated by engravings from La Nature, show 

 how the existence of surface tension may be 

 easil}- proved. 



Take a large and a small pencil, place them 

 together, and, with the aid of a small brush, 

 wet the adjoining surfaces. The tension of the 

 film of water between them, as shown at ab, 

 Fig. 1, will be sufHcient to hold the two firmly 

 together ; and, when lifted up, the smaller 

 pencil remains suspended to the larger one. 



In Fig. 2 another experiment is illustrated 

 which shows the contractile power of the sur- 

 face film. Fold a piece of thin paper into the 

 form of a little box about six inches long and 

 half an inch wide and high. On pouring 



water into it, the surface film of water will 

 draw the sides of the box together, thus prov- 

 ing that it is in a constant state of tension, 

 like a piece of stretched rubber cloth. 



It is well known, that, owing to the tension 

 existing on the surface of water, needles, 

 pens, and even small coins, may be made to 

 float if carefully placed upon it. In Fig. 3 is 

 illustrated an experiment which shows the 

 reverse of this phenomenon, and will well 

 repay the slight amount of trouble necessary 

 to prepare the apparatus. A good-sized cork 

 is taken, and to the lower end is attached a 

 small vessel, which may be conveniently made 

 out of a thimble. At the upper end is placed 

 a ring of very fine, bright, and clean iron or cop- 

 per wire, supported by two other wires fas- 

 tened into the cork. The ring should be about 

 four inches in diameter. The apparatus is 

 then placed in a vessel of water, and sand or 

 fine shot placed in the thimble until it is bal- 

 anced so that it floats with the ring from one- 

 quarter to one-half of an inch above the sur- 

 face. If the ring is then pressed down below 

 the surface, the tension of the film will be 

 great enough to prevent the ring breaking 



through it ; and it will remain just underneath 

 the surface, which is pressed up a little, and 

 rendered slightly convex. Now, if a drop of 



luCAOt 



Fio. 3. 



ether be placed inside the ring, the surface 

 tension is diminished, and the ring rises up 

 through the water as if propelled bj' an unseen 

 force. Some care is necessary to have this 

 experiment succeed, the principal precaution 

 being, to have the wire ring perfectly clean and 

 bright. It is better to slightly grease it by 

 drawing it through the fingers. 



The intense coloring power of the aniline 

 dj-es can be made the occasion of an amusing 

 experiment bj' which a white rose or other 

 flower is apparently changed to a diflTerent 

 color by sprinkling it with cologne. Some 

 aniline red or other color is finely pulverized, 

 and a very little of it previously dusted over 



FiQ. 4. 



the flower. It will be quite invisible ; but if 

 alcohol or cologne is blown over it from an 

 atomizer, the dye is dissolved, and its color 

 immediately appears. The illustration (Fig. 

 4) shows the experiment being performed 



