The Sun.
London, England, 1857-04-13 00:00:00

LON DON, MuND 'IL EVENING, APE IL 13,

711 E ROY4I, PQLYTECHNIO INSTITUTION.

On Saturday evening a private view took place of the
novelties intended for exhibition at this institution during
the Easter holidays. From 'the programme gone through
there is every reason to believe that the institution will
upon this occasion lose nothing of •the large amount of
public patronage which has hitherto _always been be-
stowed upon it during the holiday season of the year.
Mr. Pepper has been indefatigable in his 'exertions to
retnedel•the whole of hie entertainments, adding to those
whichare retained from last season new features of in-
' rerest, and supplying the places of others with new sub:
Picts,' which, apart from the score of novelty, cannot
fait to be attractive on their own merits. Foremost
among these is a new feature of daily conceits, which
Will in future be given in the institution every morning
and evening by the celebrated flunearian band, as-
sis:.:ed in the vocal department by Ad iss'Leffler and Miss
Hemming.
Mr. .Pepper's new lectures upon applied chemistry
embrace several interesting subjects, more especially one
upon the use and abuse of the fire annihilator, in which
the chemical principles involved in that useful though
much abused and misunderstood instrument are
explained and i'lustrated by a, series of interesting
experiments,. Another lecture is devoted to the ex-
planation of Mr. Rose's (of Glasgow) newly invented
optical delusion, called the kalotrepe. The inStru:
ment exhibited a number of very curious optical
delusions, 'obtained by taking advantage of the well-
known fact that an impression produced upon the retina
of the eye is retained there for a certain period after the
of itself has passed away. This fact may be observed
by any person who swings round a piece of lighted char-
coal, when it will not appear like a single piece rotat-
ing, but will assume the aspect of a circle of fire, the
impression produced from every succeeding portion of
the circlo being retained by the eye at the same time.
Advantage was taken of this phenomenon by Mr Rose,
who contrived' a series of rapidly-rotating wheels, pro-
vided with a number of different devices. By the rapid
resolution of these many curious and interesting optical
effects are produced. :Two new' and very interesting
series of dissolving views are also added to the entertain-
ments. One illustrating China and the localities of the
present war, 'which are accompanied by a lucid and
interesting lecture on the manners of the Chinese, by
A. E. Spencer, Eeq. The lecture derives additional
interest' from the fact that it clears up many obscure
points relative to the civilisation of'the Chinese people,
which have afforded matter for considerable discussion
lately. The second series illustrates Egypt In the time
of the Pharaoh, comprising a series of pictures of the
mariners and customs of the Egyptians and the Jews
at the time of the captivity. 'Art interesting original
.description of the pictures, by Mr. Leicester Buck-
ingham, accompanies. the series. The whole of the
views are executed by Mr. Hine in the most artistic
style, some of them being works of considerable merit,
the perepective in some cases being so perfect as to give
them almost a stereoscopic appearance. A dioramic
effect of the Temple of Itarnac, gradually growing out
of its ruined state into 'a perfect restoration, is really
very cleverly managed. The room in the building
which was formally occupied by the ornithological col-
lection is now devoted to the exhibition of Steven's
luminous chromatic transparencies of China and various
Leeds of Europe. The scenes are very cleverly executed,
and are undoubtedly a great addition to the attractions
of the place. They were exhibited at the Paris Exhibi-
tion of 18e5. 'Among the recent• novelties may be also
noticed Loysel's patent machine for making coffee,
which has just been erected in the refre'hment depart-
meet.. It has 'Ong been used both at the Crystal Palace
and in Paris, arid it is, therefore, unnecessary to give a
particular description of it. Suffice it to say that an
almost incredible quantity of either tea or coffee of a
very superior quality and flavour can be made in a few
minutes. In the case of tea the operation is much facili-
tated and ithe flavour improved by grinding it. This
apparatus is used in all the military hospitals of the
French army, as it is equally applicable and useful in
making decoctions of medicinal herbs, as in making the
more homely beverage above mentioned. Altogether
the Easter novelties at the Polytechnic this year are of a
more diver e and attractive nature than has hitherto
been attempted at this institution, and they will not
only afford. aneusement and instruction during one but
many visits.

CONVICTION OF AAKPRS FOR USING

ALUM.

Oa Saturday last; C. Parks, S. Marlin g,`3 . Gra-
ham, and R. Pitlake,. bakers, all of Croydon, ap-
appeared on summons before the magistrates ps-
.serabled in petty sessions—viz., T.' Byron; Eq.
(chairnaau), J. W. Sutherland, Esq., and J.. Gu-
rney, Esq., M.P. for Falmouth, charged with sell-
jog adu4tTated bread.

. Mr. Dart, inspector of 'weights and measures, his
son, and Sergeant Julian, deposed.thatthey purcliased
bread of the defendants, and c mveyecl it to Dr. Nor-
ehia,ndy, analytical chemise. Dr. Normandy sated
that he had analysed the bread produced in all tbe
cases, and that he had found it to contain a large
quantity of alum ; he . described the process by
which lie discovered. traces of a'in-, rind stated it to
be decidedly injurious to the constaption, and also
alrOrded means to bakers of defrauding the public,
as by its aid, it having the property of absorbing
water, it increased the 'weight of bread, added to
which it also enabled the baker to use's, commoner
flour, giving it the appearance of bread of the first
quality, and considerably deteriorated its nutritious
properties. •

-`lThe Bench fined all the defendants upwards of
101. each, including costs. Notice. of appeal was
given in all the cases.
Mr. Byron, the :chairman, on behalf of the ma-
gistrates, said they would persevere in, their endea-
vours to discover who were the adulterators of beer
and other articles of food in Croydon.
In his-report as medical officer of heidth to the

Holborn district, Dr. S. Gibbon gives the follow-

ing particulars to enable the purifiaser to distil]-
guish 'atoakhat-does not -contain alum froth one
which dee• :—" Alum increases the •whiteness and
firmness of the bread made from inferior flour, and
thereby cause it to resemble bread made from the

very best flour. The qualities which alum imparts
'to a loaf .are very unimportant, having reference
merely to the appearance,- lightness,' neatness, of
shape, Jsc. The chemical action of alum 'on mois-
tened flour is-analogous to tanning, and destroys in
'a considerable degree its nutritiveness. It Converts
the gluten (the most nutritious portion) of the flour
into a kind of tough tenacious wash. leather,'
which is, difficult of digestion. This' gives the dough
a tenacity and firmness, 'enabling it to retain the
thousind of little air bubbles (given off by the
.yeast) which constitutes t e 'lightness,' or spongy
porous character, of the bread. Hence flour that
will hot `rise' may be made to do so by means of
alum. Another object in the use of alum is that it
preserves the upright form of- the loaves and pre-
vents them fioin adhering firmly together, thereby
enabling the baker to separate them mote readily
on titer removal fog the oven—the batch parts
clean,' as the expression is, without tearing. An
unalumed loaf is, with a little,practice, distinguish-
able from an alumed one by its appearance alone ;
'it is Wanting in all those peculiarities which I have
mentioned as the effects of alum, it is not so bulky,
nor so symmetrical in its shape, its sides are rough-
ened and torn in being separated from the batch.
Unalumed bread 'bites short,' alumed. bread 'bites
tough,' and the rough, sour taste of alum is slightly
perceptible in it. The moat marked contrast, how-
ever, is apparent in ' crumbling,' when a day or two
old ; unalumed bread crumbles with the greatest
facility by rubbing it between the hands, whereaa
alumed bread, however old, crumbles' with diffi-
culty. In the same way alum renders the new loaf
less liable to crumble when cut. These, then, are
'the qualities and appearances in a loaf which I re-
commend the purchaser to disregard. I am not
prepared to say that these points can be fully relied
on as tests for the presenceof alum ; chemical tests
alone can justify one in declaring positively that a
loaf of bread contains alum."