1 16 Dr, Kane's Contributions to the History 



equally valid, by reducing the peculiarities to sections. Be- 

 yond this our remarks do not extend. It is the part of the 

 experienced and practical botanist to reduce classes to orders, 

 or to suborders, it' necessary, and to construct their diagnosis ; 

 or rather, perhaps, by reversing the process and advancing in 

 the line of ascent, to reduce orders or suborders to classes; 

 and to the experienced and practical botanist we are content 

 to commit the task. P. Keith. 



Charing, Kent, Feb. 15, 1835. 



XXV. Researches in Organic Chemistrij. — First Series. Con- 

 tributions to the History of Pyroxytic Spirit and of its derived 

 Combinatiotis, By Robert J. Kane, M,D,^ M.R.LA. 



[Continued from p. 51, and concluded.] 



Of the Products of the Oxidation of Pyroxytic Spirit by Sul- 

 phttric Acid and Black Oxide of Manganese. 



"1^7"HEN sulphuric acid, black oxide of manganese, and py- 

 ^^ roxylic spirit are brought into contact, the action which 

 ensues is very violent, and there is so much effervescence that 

 unless the retort be taken very large in proportion to the 

 quantity of materials used there is great danger of its boiling 

 over. By previously diluting the sulphuric acid with water, 

 allowing the mixture to cool before adding thereto the black 

 oxide of manganese and sulphuric acid, this can be to a great 

 extent avoided, and the quantity of product is also by this 

 means considerably increased. 



The proportions found most advantageous were two ounces 

 of pyroxylic spirit, three of sulphuric acid and three of water, 

 and two of black oxide of manfjanese. The mani^anese and 

 pyroxylic spirit having been first put into the retort and after- 

 vi^ards the diluted and cold sulphuric acid added, the whole 

 is to be very gently heated in a water-bath, and as soon as the 

 mass commences to froth, the fire should be withdrawn, in or- 

 der to prevent the temperature of the water from rising too 

 high, in which case the mixture is liable to boil over. Once 

 commenced, the distillation goes on almost of itself; as the 

 ebullition moderates the temperature can be again raised, and 

 the distillation continued as long as any fluid comes over, by 

 the water-bath. If the water- be then replaced by a sand-bath 

 and the receiver changed, a liquor can be obtained which is a 

 dilute formic acid. 



The product obtained by distillation in the water-bath is 

 very heterogeneous; it must be rectified in the water-bath. It 

 begins to boil under 40° centigrade, and the boiling point gra- 



