gl6 ACTION OF MURIATIC ACID ON SUGAtt. 



Indigo disoxi- A very interesting observation, for which we are indebted 

 phureuedhi- to ^ r * Vauquelin, is the disoxidation of indigo by sulphu- 

 drogen. retted hidrogen. This experiment proves two curious facts: 



1st, that in this substance either the whole or at least part 

 of the oxigen exists in some sort separate from the other prin- 

 ciples, since it may be taken away, and restored at pleasure 

 by allowing the sulphuretted hidrogen to evaporate in the 

 . ©pen air, without destroying the nature of the colouring 

 matter. In this circumstance indigo has a resemblance to 

 the metals. 2dly, that carbon has no concern in the colour- 

 ing of indigo, since this is deprived of colour in circum- 

 stances in which it contains most carbon. 



vnr. 



On the Action of Muriatic Acid on Sugar, and the Nature of 

 its Principles : In a Letter from John Nowell, Esq. 



To W. NICHOLSON, Esq. 



SIR, 



Nitric sci'l <!e- JiT is well known, that the nitric acid becomes decomposed 



ci)in;^e<lo\j • j SU p;ar under certain circumstances, and forms a vegeta- 

 t.u»ar bv yieM- n . p . 



ingin/oneof ble acid (the oxalic) by yielding to the sugar one of its 



its elements, e i emen ts. If the composition of the nitric acid was not 



the oxigen, . 



might furni-h known, this property evidently would furnish a clew to guide 



a clew for in- us m the investigation of its elementary principles. Some 

 vestigating Us . . . , 



composition, time ago I was struck with the same idea with respect.to the 



muriatic acid ; and, as its action on sugar had not been ob- 



Tha same may serV £(j with attention, I set about making experiments on 

 be said respect- * , . ... .,, i ,. • . • , 



ing muriatic the subject, with a view, it not to change the muriatic acid 



a-" 1 - into a new substance, at least to satisfy myself of the parti- 



culars of its action. 

 Dr Priestley I was aware, that Dr. Priestley had observed when mu im- 

 partially exa- & ^ Q was passe( ] through a solution of sugar it gradually 

 mined the ef- " 1,1 



fccts produced acquired a brown colour and strong smell ; but on passing a 



on sugar by rurrent f this s;as through a moderately strong soiutioti, I 

 muriatic gas. ' ' ,. , 1 c .1 



was convinced of the extreme slowness or the process. 



Besides, 



