British Guiana Exhibition. 289 
phosphate of lime from a small island near St. Vincent, 
attracted notice and a sample was handed to Mr. 
FRANCIS, Government Chemist, for analysis, but his 
departure from the colony prevented his making known 
its exact value as a manure. 
Class VII.- Arts and Manufactures. 
This Section included a great variety of specimens, 
from bricks and concrete blocks, to lace and artificial 
flowers. Mr. W. B. Green contributed a capital speci- 
men of concrete, and Mr. L. M. Hill a system of 
constructing concrete walls and building-blocks with 
internal cells formed inside the concrete mass, by the 
use of inexpensive waste material in the shape of old 
bottles, empty tins and hollow ware of all descriptions. 
The advantages claimed are a considerable saving in 
weight, materials and cost. In the examples of blocks 
exhibited, the saving in weight is as much as 41 per 
cent, but as a rule 25 to 30 per cent is all that is claimed, 
besides the saving in cost of foundations. 
In regard to the application of the system to the con- 
struction of Building-blocks, the advantage over the 
ordinary system of open cells is that a full surface is 
maintained for the mortar bed between the courses, 
instead of only a marginal surface as with open cells. 
In a country like ours where the foundation diffi- 
culty is continually present to the mind of the 
Architect and Builder lightness in a structure, 
where no material lessening of strength is conse- 
quent thereon, is a quality to be desired, and 
therefore the new system may prove of some practical 
utility in the erection of more substantial buildings in 
MM 
