556 TRANSACTIONS OF SECTION J. 
2. Forms of Precipitation of Inorganic Colloids. 
By Professor B. Moors, F.R.S. 
3. The Action of Ultra-violet Light on Solutions of Organic 
Substances. By Professor B. Moors, F.R.S. 
4. The Presence of Iron Salts * thie Colourless Portion of the 
Chloroplast, and the Mechanism of Photo-Synthesis by Iron 
Salts. By Professor B. Moors, F.R.S. 
(oa 
Note on the Deposit Sbubien ain “Milk by Spinning in a Centri- 
fuge. By H. 8. Haucro Warpnaw. 
When milk is spun in a centrifuge a white deposit accumulates in the con- 
taining vessels. The first portion of this deposit consists of cellular material, 
the remainder is composed of minute granules, less than 0:00] mm. in diameter. 
The removal of this material from milk does not raise its freezing-point. The 
composition of this deposit is not constant, but the figures given below show its 
nature :— 
100 at of dry ee contain— 
Ash . Pee ayes cet te) dea age ORD EOS 
(P?O°> . gt ata ae : a ee: . 36) 
(CaO . : $ ; : : 7 ond 
Combustible Substance ; , : ; : 3 OZ! iss 
(Caseinogen “ : : 5 5 Ds) 
(Lactose . : ‘ : : . 19) 
(Remainder : ; : : ; . 16) 
The sixteen parts of combustible substance not accounted for contain 2°5 parts of 
nitrogen, and consist, in part at any rate, of protein coagulated by boiling. 
A considerable portion of the deposit (up to 60 per cent.) is soluble in a 
volume of water equal to that of the milk from which it was removed, and the 
soluble portion contains the bulk of the ash (up to 90 per cent.). 
The percentages of ash in the deposits obtained from the sami2 sample of milk 
after various periods of spinning are not the same, but first increase and then 
decrease as the spinning is continued. With an initial percentage of ash of 
7-0 the maximum percentage was reached after about two hours’ spinning and 
amounted to 8:0. 
The rate of accumulation of this deposit also varies with the time of spinning, 
but approximately inversely to the percentage of ash, first decreasing to a 
minimum, then increasing. The average rate of deposition under the conditions 
of the experiments was about 70 mg. per hour per 100 c.c. of milk. This subse- 
quent increase in the rate of deposition is peculiar. 
6. Some Notes on the Symbiotic Activities of Coliform and other 
Organisms on Media containing Carbohydrates and Allied Sub- 
stances. By Burron BRraDLey. 
(1) Consideration of the effect of coliform aérogene organisms in company 
with coliform anaérogene-oxygene organisms on media containing a carbohydrate 
(or allied substance) not affected by the former organisms, and from which 
acid, without gas, is produced by the latter. 
(2) Consideration of the effect of coliform aérogene organisms on the sterilised 
acid or sterilised neutralised products of the action of coliform anaérogene- 
oxygene organisms, other conditions being as in (1). 
(3) Considerations of various factors concerned in the results produced. 
(4) Consideration of the symbiotic activity of other organisms. 
(5) General conclusions. 
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