C. (Strain.)
B. (Common strain.)
A. (Common.)

Unsaponifiable matter is present in rosin in varying amounts.

Below are a few typical figures taken from a large number of collated
determinations:--

________________________________________________________________
| | | | | |
| | Saponification | Total | Free | Iodine |
| | Equivalent. | Acid No. | Acid No. | No. |
|________________|________________|__________|__________|________|
| | | | | |
| American W. W. | 330.5 | 169.7 | 119.1 | 126.9 |
| American N. | 312.3 | 179.6 | 161.4 | 137.8 |
| French | 320.5 | 175 | 168 | 120.7 |
| Spanish | 313.4 | 179 | 160 | 129.8 |
|________________|________________|__________|__________|________|

ALKALI (CAUSTIC AND CARBONATED).

The manufacture of alkali was at one time carried on in conjunction with
soap-making, but of late years it has become more general for the soap
manufacturer to buy his caustic soda or carbonated alkali from the
alkali-maker.

Although there are some alkali-makers who invoice caustic soda and soda
ash in terms of actual percentage of sodium oxide (Na_{2}O), it is the
trade custom to buy and sell on what is known as the English degree,
which is about 1 per cent. higher than this.

The English degree is a survival of the time when the atomic weight of
sodium was believed to be twenty-four instead of twenty-three, and,
since the error on 76 per cent. Na_{2}O due to this amounts to about 1
per cent., may be obtained by adding this figure to the sodium oxide
really present.

_Caustic soda_ (sodium hydrate) comes into commerce in a liquid form as
90 deg. Tw. (and even as high as 106 deg. Tw.), and other degrees of dilution,
and also in a solid form in various grades as 60 deg., 70 deg., 76-77 deg., 77-78 deg.
These degrees represent the percentage of sodium oxide (Na_{2}O) present
plus the 1 per cent. The highest grade, containing as it does more
available caustic soda and less impurities, is much more advantageous in
use.

_Carbonate of soda_ or _soda ash_, 58 deg., also termed "light ash," and
"refined alkali". This is a commercially pure sodium carbonate
containing about 0.5 per cent. salt (NaCl). The 58 deg. repres