40 THE POPULAR SCIENCE MONTHLY. 



cent platinum spiral, with or without the mirror, produced musical 

 sounds. AVhen the battery power was reduced from ten cells to three, 

 the sounds, though enfeebled, were still distinct. 



My neglect of aqueous vapor had led me for a time astray in 1859, 

 but before publishing my results I had discovered my error. On the 

 present occasion this omnipresent substance had also to be reckoned 

 with. Fourteen flasks of various sizes, with their bottoms covered 

 with a little sulphuric acid, were closed with ordinary corks and per- 

 mitted to remain in the laboratory from the 23d of December to the 

 4th of January. Tested on the latter day with the intermittent beam, 

 half of them emitted feeble sounds, but half were silent. The sounds 

 were undoubtedly due, not to dry air, but to traces of aqueous vapor. 



An ordinary bottle, containing sulphuric acid for laboratory pur- 

 poses, being connected with the ear and placed in the intermittent 

 beam, emitted a faint but distinct musical sound. This bottle had 

 been opened two or three times during the day, its dryness being thus 

 vitiated by the mixture of a small quantity of common air. A second 

 similar bottle, in which sulphuric acid had stood undisturbed for some 

 days, was placed in the beam : the dry air above the liquid j)roved 

 absolutely silent. 



On the evenin gr of Januarv 7th Professor Dewar handed me four 

 flasks treated in the following manner : Into one was poured a small 

 quantity of strong sulphuric acid ; into another a small quantity of 

 Nordhausen sulphuric acid ; in a third were placed some fragments 

 of fused chloride of calcium ; while the fourth contained a small 

 quantity of phosphoric anhydride. They were closed with well-fitting 

 India-rubber stoppers, and permitted to remain undisturbed through- 

 out the night. Tested after twelve hours, each of them emitted a 

 feeble sound, the flask last mentioned being the strongest. Tested 

 again six hours later, the sound had disappeared from three of the 

 flasks, that containing the phosphoric anhydride alone remaining 

 musical. 



Breathing into a flask partially filled with sulphuric acid instantly 

 restores the sounding power, which continues for a considerable time. 

 The wetting of the interior surface of the flask with the sulphuric 

 acid always enfeebles and sometimes destroys the sound. 



A bulb, less than a cubic inch in volume, and containing a little 

 water, lowered to the temperature of melting ice, produces very dis- 

 tinct sounds. Warming the water in the flame of a spirit-lamp, the 

 sound becomes greatly augmented in strength. At the boiling tem- 

 perature the sound emitted by this small bulb * is of extraordinary 

 intensity. 



These results are in accord with those obtained by me nearly nine- 

 teen years ago, both in reference to air and to aqueous vapor. They 



* In such bulb3 even bisulphidc-of -carbon vapor may be so nursed as to produce 

 sounds of considerable strength. 



