234 
Instructions to the 
products of all kinds. It is in this way only that the re¬ 
sources of foreign countries can be ascertained, and it is pre¬ 
sumed that in an expedition which will be stationary for con¬ 
siderable periods of time, such inquiries can be easily made. 
Under the head of useful products the following may be par¬ 
ticularly mentioned:— 
1. Dietetical , medicinal , and poisonous agents of all kinds. 
The nature and action of the poisons employed by the natives 
of many countries are but slightly known. 
2. Dye staffs . Attention should be paid especially to ob¬ 
tain lichens, as substitutes for the Roccella tinctoria, now 
becoming scarce, and consequently very valuable in European 
commerce. The fitness of these plants for this purpose may 
be approximately ascertained by Helloes lichen test, which is 
as follows :—Digest the lichen at a temperature of 130° F. for a 
few hours, in a weak solution of ammonia, but sufficiently 
strong to be tolerably pungent. One that is fit for the dyer 
will yield a rich violet red liquid. 
3. Astringent substances adapted for tanning . It is desirable 
to ascertain with accuracy the source of the various astringent 
extracts imported from New Holland and the neighbouring 
parts, and which are employed by the tanners of this country. 
4. Fibres adapted for cordage and weaving . Substitutes for 
hemp are very desirable. Great strength, flexibility, and 
freedom from injurious influence in working, are three essential 
qualities of good hemp. 
5. Information respecting the source of many of the orna - 
mental ivoods imported from the southern hemisphere is very 
imperfect. It is desirable, therefore, that inquiries be made on 
this subject, as well as for new kinds of wood. 
6. Gums, resins, volatile oils, fecula. Especially the source 
of some resins brought to this country from New Holland, and 
which are analogous in some properties to the yellow resin of 
that country. 
In forming collections of such objects, especial care must be 
taken when collected to number alike both the products and 
the plants by which they are furnished, and to note whatever 
can be learned concerning them, more particularly with regard 
to their abundance, and the facility with which they can be 
procured. It is also necessary that the observations made by 
the Botanist himself should be carefully distinguished from 
such information a9 he may receive from other persons. 
No opportunity is to be lost of collecting information respect¬ 
ing the source and mode of preparation of any vegetable sub¬ 
stances known in commerce; for many exotic products, even 
those with which we are most familiar, have many points con¬ 
nected with their natural history deserving attention. 
The vegetation of South Shetland cannot be expected to 
