574 
Supplement to the '* Tropical 4gncuUuri$t." Peb, 1^02, 
there will usually be ample scope for using all the 
available poudrette on land which lies out of reach 
of the drains. 

MEMS ABOUT MILK. 
■'There is probably no substance of which sO 
many analyses have been made as milk, and 
consequently its composition and variations of 
composition are pretty well known. 
The following taide, based on the authoritj* 
of Keii h and Richmond, gives tr.e average com- 
position of pure new milk ; Fat 4'0, proteids 
3*6, 8ng;ir 4"5, ash 07, total non-fatty solids 
8-8, water 87-2. 
The fat in milk is ofcourse what confers on it its 
riches. The sugar is a special vuiiety to which 
the name of lactose has been given. It differs 
from cane sugar in that it is far less sheet, 
and hence it is not so powerful a flavouring 
agent as the latter. The proteid matter, like 
the white of egg, has no very pronounced taste, 
but yet it confers on milk a fullness and round- 
ness of flavour, which a simple solution of 
lactose in water would not possess. New milk 
thus gives richness through its fat, sweetness 
through its sugar, and what may be called 
mellovfiiees through its proteids. Separated milk is 
practically ntw milk less its fat. 
Tha composition of new milk has been indi- 
cated in the analysis already quoted, but these 
figure* must not be received as by any means the 
lowMt obtainable from undoubtedly pure sam- 
ples. For the purposes of the Food and Drug* 
Adulteration Act, the limits in England have 
recently been adopted of 3 per cent fat and 8 "5 
per cent solids not fat. In th« case of a milk 
falling below these limits, the onus of proof of 
iti purity lies with the vendor. But a direct 
estimate of value is of more importance than 
knowing whether or not a particular (lample of 
milk passes the limits of the public analyst. 
Thue milks containing respectively 3 and 4 per 
cent of fat, would so far as the fat ig concerned, 
be passpd as free from adulteration ; but it is 
obv ious that the former sample has three-fourths 
the value of the latter. For some years this 
subject of the valuation of milk has engaged 
the attention of Mr. William Jago V.G,S., F.i.c, 
■who suggests, and has for some considerable 
time employed, a standard of valuation worked 
out on the following lines : — From an examination 
of a considerable number of commercial milks 
an average conventional standard of quality was 
first determined, the aim being not to go so 
low as the Government limit for adulteration, 
but to take figures which a buyer might reason- 
ably demand to be reached in milks supplied 
to him. These were ultimately taken as being 
for new milk. Total solids 1S"5, fat 3'5, non- 
fatty solids 9-0. 
Where both new and separated milk are market- 
able products it would be possible to value the 
constituents, thus: Taking the market value of 
new milk at 10c?. per gallon, and separated milk 
at 2^d, per gallon, and the difference between 
the quality of the two as being an excess of 
3-2 per cent fat ia new milk, then the excess of 
fat must be given a value of l^d., and in the 
same proportion 3 '5 per cent fat would be 
worth 8'2c?. From this llie value of the convential 
Ktandiird sami'les esn beexpres<-ed iu terms of their 
constituents, this ii, iu new milk 3'5 per cent 
faf=8-2f/., 9 per cent non-fats=l-8(i. or lOd. the 
gallon. 
If the value of the standard be called 100, 
then the value of any sample can from the 
analysis be expressed in terms of percentages 
of th« standard. For instance, the 8*6 of 
fat would be represented by the standard percen- 
tage 82 (?.«., of the total of valuable constituents) 
and 9-0 non-fatty solids by the standard per- 
centage 18, This will enable two tables to be 
drawn up for comparative valuation of fat and 
non-fatty solids in terms of the standards. 
We give below the standard figures and those 
in three other cases for the purposes of com- 
parison : — 
Description. 
, a 
a -2 
o . - 
O g 
1. Jlr. Jago's couventive standard , 
Fat ... 3-5 82-00 
Solids not fat 9-0 18-00 
12-5 10000 10-Od 
2. Present Government limit : 
Fat ... 3-0 
Solids not fat 8'o 
11-5 
70-29 
17-00 
87-29 
8-7d 
3. Very rich milk watered : 
Fat ... 4-3 100-72 
Solids not fat 8-1 16-20 
12.4 116-92 IVld 
Unsweetened milk diluted to 
three times its volume : 
Fat ... 3-5 
Solids not fat 8-2 
82-00 
16-40 
11-7 98-40 
9-8d 
Looking at No. 3, it will be seen that the 
milk though of the highest value in terms of 
the standard, shows nevertheless evidence of 
having been watered, and would probably be 
made the subject of a prosecution if analysed 
for the purpose of the Food and Drugs Act. 
The public analyst being concerned simply with 
adulteration, while the commercial user is more 
vitally interested in the question of actual 
value. 
In ascertaining the value of condensed milks 
it is usual to dilute them to three times their 
original volume. Then such a milk as No. 4 
is, as nearly as possible, of the same degree 
of eoncentration as the standard milk. 
[We are indebted for the information in 
the above to Mr. William Jago's lectures on 
the Chemistry of Confectioner's Materials and Pro- 
cesses, delivered before the Society of Arts last 
November.— Ed, A.M^[ 
