Clifton College Scientific Society. 85 



exception of triplumbic diosyacetate (Pb302(C2H30j2)- The 

 product of the oxidation of oil of turpentine (C,2H,g) is a 

 resinous substance ; of oil of bitter almonds (C^HgO) benzoic 

 acid (C7Hg02) ; of alcohol (C2HgO) formic acid (CHgOa) ; of 

 tannic acid (02711220,7) oxalic acid (HgCgO^), &c. ; blood is so 

 acted upon as to leave scarcely anything but a mineral 

 residue. The presence of an alkali in all cases accelerates 

 the oxidation of an organic substance by ozone. 



The oxidizmg j^roperties of ozone are in almost all cases 

 the basis upon which the tests for identification are founded. 



(1) The iodine starch test paper is prej^ared as follows : — 

 Slips of bibulous paper are smeared with the following com- 

 position ; 1 drachm of white starch (CgHj^Oj) mixed with 1 

 oz. of boiling water and the solution boiled, then 12 grains 

 of potassic iodide (KI) are to be added, and the whole well 

 mixed together. Schoubein recommends the proportions of 

 1 part of potassic iodide, 10 of starch, and 200 of water. 



The prepared paper should be kept in a stoppered bottle 

 covered with tinfoil to exclude hydric sulphide (H2S), am- 

 monia (NH3), nitrous and nitric acid (HNOj and HNO3), and 

 light, otherwise a loss of colour will be the consequence. 



The presence of potassic iodate in the iodide must be 

 avoided, or conflicting results will be recorded in the pre- 

 sence of sulphurous acid (SO2) and sulphuretted hydrogen 

 (H2S), gases of frequent occurrence in the air. 



Ozone is indicated by the decomposition of the potassium 

 salt, iodine being liberated, which combines with starch to 

 form the blue iodide of starch. But since the same result 

 follows from the presence of many other substances, the 

 test, although extremely sensitive, is by no means charac- 

 teristic. M. Houzeaii has proposed a modification of this test, 

 namely, red litmus paper dipped in a solution of potassic 

 iodide ; when decomposed the potash (KHO) will change the 

 red litmus paper to blue ; a piece of red litmus (without 

 potassic iodide) must be suspended near, in order to see if 

 any ammonia is present which would produce the same 

 result. 



M. Fremy has devised a test, consisting of blotting paper 

 dipped in an alcoholic solution of guiacum (CgH^NgO + CH^lSTg, 

 &c.) dried in the dark. 



Paper soaked in manganous sulphate (MnS04) indicates 

 £he presence of ozone by becoming brown ; this is due to the 

 absorption of oxygen, by which moans the salt is converted 

 into the hydrated peroxide (MnH^Oj) and free sulphuric 

 acid (HaSOj. 



