648 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



passed up through the oil which was not condensed; this was proved to be 

 nitrogen. To avoid any suspicion about boiling by electrical means, simi- 

 lar experiments were made with similar results, in which the boiling was 

 produced by a spirit lamp. He was led to try the effect of boiling an 

 elementary liquid and bromine occurred as the most promising one to work 

 upon. The temperature of the bromine was first raised, until its vapor 

 had driven all the air from the glass tube, when it was sealed by the blow- 

 pipe. The bromine vapor, on condensing, left a vacuum above it. After 

 boiling, a notable quantity of a permanent gas was found to have 

 collected in the tube which proved to be pure oxygen. The experiment 

 was repeated with chloride of iodine with the same result, only the quan- 

 tity of oxygen was greater. Mr. Grove also described his fruitless 

 attempts to obtain in this way the vapors of phosphorus and sulphur. 

 He barely alluded to results on the compound liquids, such as oils and the 

 hydro-carbons, as the fact that permanent gas is given off in boiling such 

 liquids would not be unexpected; but the other experiments seem to show 

 that boiling is by no means necessarily the phenomenon that has generally 

 been supposed, viz.: a separation of the cohesion in the molecules of a 

 liquid from distension by heat. 



He believes, from the investigation he has made, that (except with 

 metals on which there is no evidence) no one has seen the phenomenon of 

 pure boiling water without permanent gas being freed, and that what is 

 ordinarily termed boiling arises from the extracting of a bubble of perma- 

 nent gas, either by the chemical decomposition of the liquid, or by the 

 separation of some gas, associated in minute quantity with the liquid, and 

 from which human means have hitherto failed to purge it: this bubble 

 once extracted, the vapor of the liquid expands it, or to use the appropri- 

 ate phrase of Mr. Donny, the liquid evaporates against the surface of the 

 gas. 



Mr. Grove's experiments are in a certain sense the complement of those 

 of Mr. Donny. The latter showed that the temperature of the boiling point 

 was raised in the same proportion as water was deprived of air, and that ' 

 under sucb circumstances the boiling took place by soubresaut. The former 

 has shown that when the vapor liberated by boiling is allowed to condense, 

 it does not altogether collapse into a liquid, but leaves a residual bubble 

 of permanent gas, and that at a certain point this evolution becomes uni- 

 form. Boiling, then, is not the result of merely raising a liquid to a given 

 temperature; it is something much more complex. Enough had been 

 shown by his experiments to lead to the conclusion that hitherto simple 

 boiling, in tiie sense of a liquid being expanded by heat into a vapor with- 

 out being decomposed or having a permanent gas eliminated from it, is a 

 thing unknown. Whether such boiling can take place may be regarded as 

 an open question. He was inclined to think it cannot; that if water, for 

 instance, be absolutely deprived of its nitrogen, it would not boil imtil 

 some portion was decomposed; that the physical severance of the mole- 

 cules by heat is also a chemical severance. The constant appearance of 

 nitrogen in water, when boiled off, out of contact with the air, almost to 

 the last drop, is a matter well worthy of investigation. He would not 



