12' Historical Sketch of Improvements in [JuxV,-^ 



tion ammonia, taking care that the two hquids do not intermix.' 

 In a short time the fodine crystaUizes between the two hquids in " 

 beautiful pyramids whose bases are turned towards the surface 

 of the hquid. A shght agitation makes these crystals imme- 

 diately disappear. — (Jour, de Pharm. vi. 95.) 



Dr. Andrew Fyfe, of Edinburgh, has made some experiments 

 to determine the sulDStances which contain iodine. The follow- 

 ing are the results of his researches : 



(1.) Iodine cannot be detected in sea-water. 



(2.) It is confined to marine productions alone. 



(3.) He procured it from the fucus nodosus, fucus serratus, 

 fucus palmatus, and fucus digitatus. He obtained it also from 

 the ulva umbilicalis, and from a species of conferva. The fucus 

 vpsiculosus would not yield him any. 



(4.) Ts^either oysters nor coral yielded him any ; butthe common 

 sponge of the shops yielded it when treated in the usual way. — 

 <Edin. Phil. Jour. i. 254.) 



VI. Simple Combustibles. 



1. Hi/drogeii. — I noticed in the historical sketch of last year, 

 that a careful set of experiments on the specific gravity of 

 hydrogen gas, made in my laboratory, gave for the result, 

 0-06933. This comes very near to the number deduced by Dr. 

 Prout from the specific gravity of ammonia. It establishes, 

 therefore, the relative specific gravities of hydrogen and oxygen 

 gases to each other as 1 to 16. Hence it follows that exactly 

 one-ninth of the weight of v^'ateris hydrogen, while eight-ninths 

 are oxygen. 



I propose very soon to give a set of careful experiments, 

 which have been made in my laboratory, to determine the speci- 

 fic gravity of the gases. 



2. Sulphur. — The only addition to the histoiy of sulphur with 

 which I am acquainted is the analysis of the chloride of sulphur, 

 which I published in the last number of the Avnals of Pkilosophij. 

 I was myself a good deal gratified with the results which I 

 obtained, and they will be viewed by chemists as of some value, 

 because they account for the different properties of the chloride 

 of sulphur as obtained by different chemists. 



Chloride of sulphur obtained by passing a current of chlorine 

 gas through flowers of sulphur till they are converted into a 

 liquid is a compound of one atom chlorine + two atoms sulphur. 

 Hence it is a subbichloride of sulphur. Its constituents are : 



Sulphur 4-0 or 47-06 



Chlorine 4-5 52-94 



100-00 



When agitated in water, one half of the sulphur separates, the 

 other half is changed into hyposulphurous acid ; while the chlo- 



