3i6 
I^uisunoKs Cheese. 
use of solder and of skilled labour is dispensed with, the readjust- 
ment of one or two lengths much facilitated, whilst it is found 
in practice that for any given bore, required for any purpose, 
one-fifth less iron may be employed than has been usual. The 
pipes of all sizes now laid down for the Paris Waterworks are 
thus united. 
XXI. — On Poisonous Cheese. By Dr. Augustus Voklckeu. 
About two years ago, one of my assistants, soon after having 
partiskcn of some cheese, was attacked with violent vomiting 
and purging. Several other persons who had eaten of the same 
cheese were similarly affected. On inquiry, the grocer by whom 
the cheese was sold stated that, in all probability, the dairymaid 
had used a little too much vitriol in making this cheese. I was 
not aware till then that anything so injurious as vitriol was ever 
thus used ; but the readiness with wliich this supposition was 
expressed shows that at least in some quarters this injurious 
suljstance is openly put into cheese for some purpose or other. 
The chemical examination of the poisonous cheese showed 
the presence of white vitriol, or sulphate of zinc, — a compound 
highly injurious to health. On further inquiry, I learned that 
this compound is occasionally used for the purpose of giving 
fresh cheese the peculiar biting taste of old. Many other 
samples were subsequently analysed by me ; and, although the 
great majority were perfectly free from any poisonous matter, in 
one or two I found sulphate of zinc, and in a few others blue 
vitriol, or sulphate of copper, which, perhaps, is a still more 
poisonous compound. 
It appears that blue vitriol is employed to prevent heaving. 
A dairy farmer in our neighbourhood informed me that on his 
farm, in his father's time, it was employed in small quantities 
for that purpose. On taking possession of the farm, he, knowing 
blue vitriol to be injurious to health, directly forbade its use, 
but found it difficult to prevent his dairymaid from abstracting 
some of the blue vitriol which was used for pickling the seed- 
wheat. In the opinion of this gentleman, many dairymaids use 
blue vitriol ; and his view is confirmed by others, as well as 
by the actual detection by me of this j)oisonous matter in several 
samples of cheese. 
In most cases, no doubt, this is done in ignorance of its dele- 
terious properties ; and it is for this reason that I would draw 
attention to this objectionable practice. 
I am told alum is sometimes used for the same purpose, but I 
