NOTICES OF MEETINGS. 39 
DIATOMACEA, &C. 
Arranged Diatoms ... tt re “pe .... Thomas W. Bruce 
Desmids and Diatoms ... a an ... George F. Healey 
Diatoms, various... ats os ae aa Pain baker 
POLARISCOPE OBJECTS. 
Crystals aoe ws at 58s ae ane ... Dr. Symes 
Do. ne aes ae Aye sn ot A. E. Fletcher 
Platino-cyanide of Yttrium .. sie he ... Alfred Leicester 
MISCELLANEOUS, 
Electric Fluid under the Microscop ...  W. H. Okell (Chester) 
Micro-Photographs ... 06 Sor ae E. G. Tooker 
Nature prints, &c. ... vag ev us. J. Price, M.A. (Chester) 
Photo of Pond Life shown under Graphoscope C. R. Griffiths (Chester) 
Specialities in Polarizing Apparatus oe one Se ae 
Washington Teasdale, F.R.M.S. (Leeds) 
MANCHESTER MICROSCOPICAL SOCIETY.—At the meeting of the 
Manchester Microscopical Society, held on Thursday evening, December 16th, 
at the Mechanics’ Institution, Mr. Thomas Brittain, Vice-President, presiding :— 
Mr. A. W. Duncan read a paper on Cocoa and its Adulterations, being a 
continuation of a paper on Coffee and its Adulterations read at a previous 
meeting. He described the cocoa tree (Zeobroma cacao) as growing chiefly in 
Mexico, the West Indies, and South America, great care being taken in the 
cultivation of the young plant, so as to produce healthy, strong, fruit-producing 
trees of seven or eight years’ growth, previous to which time the flowers are 
periodically nipped off. A peculiarity of the tree is that it produces leaves, 
flowers, and fruit together, necessitating the gathering of fruit at different times. 
The cocoa bean contains half its weight of fat, a considerable quantity of which 
is extracted from the higher priced qualities. This fat is solid at ordinary 
temperatures, and does not turn rancid however long kept. After dealing with 
the microscopical structure of the cocoa fruit with the aid of diagrams and the 
black-board, Mr. Duncan referred to articles used as adulterants, such as animal 
fat, chalk, chicory, brick-dust, venetian red, peroxide of iron, starch, and sugar. 
Animal fat, starch, and sugar, however, are the usual adulterations. Starch, 
by forming a mucilage and surrounding the particles of cocoa really holds it in 
suspension whilst being drank. It also prevents the fat from running together 
and forming on the top of the cup as quickly as it would otherwise do. 
Dr. Samelson, the Chairman, and others took part in the discussion after- 
wards, which was practically a resumé of arguments concerning Mr. Duncan’s 
previous paper on Coffee. Some curious facts were elicited respecting various 
cheap coffees and coffee compounds sold as ‘‘ French coffee,” ‘“ Dandelion 
coffee,” and others. One cheap mixture, sold at tenpence per pound, con- 
tained only five per cent of coffee; other samples contained from forty-five to 
eighty-five per cent of chicory, besides other ingredients. 
A vote of thanks was accorded Mr. Duncan for his paper, and for a contribu- 
tion of slides for the Society’s cabinet ; also to Mr. Levy Tetlow for samples of 
peat-bog from Oldham, which has been the subject of considerable attention 
lately, and is rich in fossiliferous vegetation. 
The Chairman said his attention had been called by Mr. R. Graham to an 
article for cleaning jewellery, and described as a curious natural production, 
under the name of Silicon. This was nothing more nor less than a small solid 
aap of diatoms. A shilling box contained sufficient to mount thousands of 
slides. 
The meeting having resolved itself into the usual conversazione, the remainder 
of the evening passed in the examination of various objects, including some 
beautiful slides of foraminifera, by Mr. T. W. Lofthouse; marine algz and 
