V O L U M E 25, NO. 3, M A R C H 1 9 5 3 methods may be applied to one microscopic specimen t o gain as much information as possible. Examination of Questioned Documents.
Analytical techniques for fluorine in various materials were referred to, together with methods for assessing fluorine hazards and the need for further research into control measures.
J. .1. C. MCCLELLAND.
Examination of documents which may have been mishandled so as to convey an impression different from that originally intended is carried out. This involves such processes as the reproduction of erased writing, and the detection and presentation of added or altered particulars or of markings which have been faintly imprinted on documents. Other articles which may bear obliterated or altered impressions may also require examination. The presence of materials foreign to the article under examination may also give valuable information as to the nature of any mistreatment which may have taken place. The methods employed for this work involve the use of various types of illumination which are obtained by means of light filters or special types of lamps. Thus for working in the infrared region, a suitable filter and photographic plate are used, while the appropriate color filter is needed for the reproduction of marks on a colored object. For working in the ultraviolet region a suitable lamp is employed. The examination of typescript will usually reveal characteristics which should enable the identification of a certain machine: when this is possible any documents typed on one specific instrument can usually he considered to emanate from the same source. .Any evidence which may be obtained as a result of these inrestigat i r i i i q is reproduced in a manner suitable for presentation as evidence iii :t (,oiirtof law.
.It t h c genwal nierting of t h e Biological Methods Group, held in T.ondon December 11, two papers were presented and discussed Method of Identifying the Presence or Absence of Splenin A and GREENEA N D Splenin B in Serum Using Guinea Pigs. RAYMOSD JOSEPHINE \-.4UGH.iS-MORGAN. ’ The variation of bleeding time in guinea pigs living under controlled conditions was established. Injections were made of the chloroformsoluble Splenin A of normal serum and the acetone-soluble Splenin B from the serum of patients with rheumatoid arthritis, and the effect on the normal bleeding time noted. -4 description of the method was given, followed by a discussion of the difficulties encountered and tlie reasons for carrying out the investigation. Application of Large Plate Methods to Microbiological Assays of Antibiotics and Vitamin Products. K. A. LEES AND J. P. R. TOOTHIT I..
PXECISIOX ASS.
