Report of Society's Meetings. 193 



A letter from Mr. W. Fawcett, Jamaica, was read, 

 thanking the Society for electing him a Corresponding 

 Member. 



Mr. Abell's paper, read at the previous meeting, having 

 been declared open to discussion : — 



The Secretary read the following communication from 

 Mr. Scard, who had gone to Trinidad and was therefore 

 unable to be present : — 



Before proceeding to the subjeft matter of Mr. Abell's paper, I must 

 express my regret that absence from the colony has prevented my further 

 acquaintance with it in print. I have, therefore, to rely on the memory 

 of it as read, and plead this as an excuse for any error of omission or 

 commission in discussing the points raised. 



So far as I remember, the paper deals more with certain conditions 

 arising in the life of a Multiple Effeft than with the question adduced 

 in my original paper on the subjeft of relation of temperatures, although 

 in dealing with the one it touches somewhat on the other. 



The points which Mr. Abell has given prominence to are: istly, 

 corrosion of tubes of calandria by gases liberated from juice ; and 

 2ndly, masking of heating surface by these gases. 



The phenomenon which was chiefly dwelt upon and illustrated, the 

 corrosion of the upper parts of tubes of calandrias, is one which has 

 long been recognized as existing where yellow sugar is made, and, if I 

 mistake not, the instances given were from Faftories commonly making 

 this variety. The corrosion results from volatile acids liberated from 

 the juice by stronger acids added in the course of manufafture, and 

 which become boiled out of the juice as heating and concentration goes 

 on. The aftion on the galvanized roofing of clarifier lofts so commonly 

 seen with the making ot yellow sugar, and erroneously attributed to the 

 sulphurous acid itself, is an illustration of this. 



The greater part of these volatile acids, which appear to be given off 

 mostly in the ist and 2nd bodies of the Effeft, are condensed with the 

 calandria water. There is no doubt, however, but that a considerable 

 proportion hovers about the top of the calandria, leading to the corrosion 

 of tubes and stays noticed. 



Mr. Abell alludes to the varying amount of the corrosion observed; 

 being almost nothing in some instances. This is accounted forty the vary. 



BB 



