1887. | Permanganic Acid. 109 
water was added to a small quantity of the finely ground mixture 
of permanganate and boric anhydride a considerable evolution of 
heat occurred, and a comparatively large quantity of pink liquid 
condensed in the upper part of the test tube. The fused mixture 
of boric anhydride and potassic permanganate was a glassy mass 
of a fine purple colour, msoluble in water, or at any rate com- 
municating no colour to water when boiled with it for a few 
minutes. It was but slowly decomposed by aqua regia in the 
cold, but with greater rapidity upon boiling. It appeared to 
impart its colour to the glass of the tube in which it was formed. 
Gi) Potassium permanganate was also heated with anhydrous 
copper sulphate, and with potassic bichromate, but in neither case 
were results of a definite character obtained. 
Assuming that the pink vapours obtained in these experi- 
ments were identical with those obtained when permanganate is 
heated with slightly diluted sulphuric acid, the evidence obtained 
seems to point to the fact that these vapours are permanganic 
acid rather than permanganic anhydride, since no appreciable 
amount of coloured vapour is produced unless some water be pre- 
sent in each case. 
Though the methods above described for the preparation of 
permanganic acid have the advantage over that of Terreil in being 
unattended with danger, the yield by them is so small that it was 
deemed advisable in the subsequent experiments to employ the 
old method. Though several violent explosions occurred, they 
were not accompanied by serious results. 
The first experiment made in this manner had as its object to 
determine, if possible, the composition of the crystalline distillate 
obtaimed when permanganate is gently heated with monohydrated 
sulphuric acid. 
For this purpose a small retort, with a long, gently-tapering 
neck, was taken, and three test tubes, which slid easily over the 
neck, were chosen, and fitted with small corks, marked A, B, and 
C, that they might be readily distinguished. A small lip was 
made on one side of the edge of each test tube, so that when the 
retort neck reached nearly to the bottom of the tube a channel 
should be left between the neck of the retort and the side of the 
test tube. The acid used was pure redistilled sulphuric, diluted 
with the requisite quantity of distilled water. The potassium 
permanganate was in all cases dried at 100° C. before being used. 
The operations were conducted as follows:—The retort, con- 
taining a few grams of permanganate, was held in a clamp, so that 
the body dipped to the depth of two or three cm. into cold water, 
contained in a hemispherical bath of copper. One of the test 
tubes, whose weight, together with that of its cork, had been 
accurately determined, was deprived of its cork, and slipped over 
